Re: [CentOS] login case sensitivity
Stephen John Smoogen wrote: On 7 September 2017 at 16:07, Alexander Dalloz wrote: Am 07.09.2017 um 20:07 schrieb hw: Gordon Messmer wrote: On 09/07/2017 08:11 AM, Stephen John Smoogen wrote: This was always problematic because DNS hostnames and email addresses in the RFC standards were case insensitive Not quite. SMTP is required to treat the "local-part" of the RCPT argument as case-sensitive, and to preserve case when relaying mail. The destination is allowed to treat addresses according to local policy, but in general SMTP is case sensitive with regard to the user identifier. Last time I checked, RFCs said that local parts *should not* be case sensitive, and cyrus defaulted to treat them case sensitive, which is a default that usually needs to be changed because senders of messages tend to not pay any attention to the case sensitiveness of recipient addresses at all, which then confuses them like any other error. The relevant part from the RFC: https://www.ietf.org/rfc/rfc5321.txt 2.4. General Syntax Principles and Transaction Model Verbs and argument values (e.g., "TO:" or "to:" in the RCPT command and extension name keywords) are not case sensitive, with the sole exception in this specification of a mailbox local-part (SMTP Extensions may explicitly specify case-sensitive elements). That is, a command verb, an argument value other than a mailbox local-part, and free form text MAY be encoded in upper case, lower case, or any mixture of upper and lower case with no impact on its meaning. The local-part of a mailbox MUST BE treated as case sensitive. Therefore, SMTP implementations MUST take care to preserve the case of mailbox local-parts. In particular, for some hosts, the user "smith" is different from the user "Smith". However, exploiting the case sensitivity of mailbox local-parts impedes interoperability and is discouraged. Mailbox domains follow normal DNS rules and are hence not case sensitive. for maximum interoperability, a host that expects to receive mail SHOULD avoid defining mailboxes where the Local-part requires (or uses) the Quoted-string form or where the Local-part is case- sensitive. Thanks for the clarification to my original email. I misremembered RFC821 and thought it was for the entire part.. Commands and replies are not case sensitive. That is, a command or reply word may be upper case, lower case, or any mixture of upper and lower case. Note that this is not true of mailbox user names. For some hosts the user name is case sensitive, and SMTP implementations must take case to preserve the case of user names as they appear in mailbox arguments. Host names are not case sensitive. RFC2821, section 4.1.2: " for maximum interoperability, a host that expects to receive mail SHOULD avoid defining mailboxes where the Local-part requires (or uses) the Quoted-string form or where the Local-part is case- sensitive. " It comes down to that case-preservation is demanded from the implementations of protocols while, pragmatically, local parts are encouraged to be case insensitive. More than a decade ago, I argued that the default used by cyrus be changed to treat local parts case insensitve. About 2 years ago, that still hadn´t changed. So everyone deploying cyrus, be aware. Other than that, cyrus always worked flawlessly, and I highly recommend it to everyone needing an IMAP server. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] login case sensitivity
Alexander Dalloz wrote: Am 07.09.2017 um 20:07 schrieb hw: Gordon Messmer wrote: On 09/07/2017 08:11 AM, Stephen John Smoogen wrote: This was always problematic because DNS hostnames and email addresses in the RFC standards were case insensitive Not quite. SMTP is required to treat the "local-part" of the RCPT argument as case-sensitive, and to preserve case when relaying mail. The destination is allowed to treat addresses according to local policy, but in general SMTP is case sensitive with regard to the user identifier. Last time I checked, RFCs said that local parts *should not* be case sensitive, and cyrus defaulted to treat them case sensitive, which is a default that usually needs to be changed because senders of messages tend to not pay any attention to the case sensitiveness of recipient addresses at all, which then confuses them like any other error. The relevant part from the RFC: https://www.ietf.org/rfc/rfc5321.txt 2.4. General Syntax Principles and Transaction Model Verbs and argument values (e.g., "TO:" or "to:" in the RCPT command and extension name keywords) are not case sensitive, with the sole exception in this specification of a mailbox local-part (SMTP Extensions may explicitly specify case-sensitive elements). That is, a command verb, an argument value other than a mailbox local-part, and free form text MAY be encoded in upper case, lower case, or any mixture of upper and lower case with no impact on its meaning. The local-part of a mailbox MUST BE treated as case sensitive. Therefore, SMTP implementations MUST take care to preserve the case of mailbox local-parts. In particular, for some hosts, the user "smith" is different from the user "Smith". However, exploiting the case sensitivity of mailbox local-parts impedes interoperability and is discouraged. Mailbox domains follow normal DNS rules and are hence not case sensitive. That´s the implementation of the protocol, see my previous post, and: " Any system that includes an SMTP server supporting mail relaying or delivery MUST support the reserved mailbox "postmaster" as a case- insensitive local name. " also from RFC 2821, section 4.5.1. Of course, this is a special case; I just can´t find the part wich exactly said that local parts should be treated case insensitively beyond what I found in 2821. It´s even possible that it was changed. If you really want to treat local parts case sensitive, you can do so. I´d advise against it. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
Mark Haney wrote: On 09/07/2017 01:57 PM, hw wrote: Hi, is there anything that speaks against putting a cyrus mail spool onto a btrfs subvolume? I might be the lone voice on this, but I refuse to use btrfs for anything, much less a mail spool. I used it in production on DB and Web servers and fought corruption issues and scrubs hanging the system more times than I can count. (This was within the last 24 months.) I was told by certain mailing lists, that btrfs isn't considered production level. So, I scrapped the lot, went to xfs and haven't had a problem since. I'm not sure why you'd want your mail spool on a filesystem and seems to hate being hammered with reads/writes. Personally, on all my mail spools, I use XFS or EXT4. OUr servers here handle 600million messages a month without trouble on those filesystems. Just my $0.02. Btrfs appears rather useful because the disks are SSDs, because it allows me to create subvolumes and because it handles SSDs nicely. Unfortunately, the SSDs are not suited for hardware RAID. The only alternative I know is xfs or ext4 on mdadm and no subvolumes, and md RAID has severe performance penalties which I´m not willing to afford. Part of the data I plan to store on these SSDs greatly benefits from the low latency, making things about 20--30 times faster for an important application. So what should I do? ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
PS: What kind of storage solutions do people use for cyrus mail spools? Apparently you can not use remote storage, at least not NFS. That even makes it difficult to use a VM due to limitations of available disk space. I´m reluctant to use btrfs, but there doesn´t seem to be any reasonable alternative. hw wrote: Mark Haney wrote: On 09/07/2017 01:57 PM, hw wrote: Hi, is there anything that speaks against putting a cyrus mail spool onto a btrfs subvolume? I might be the lone voice on this, but I refuse to use btrfs for anything, much less a mail spool. I used it in production on DB and Web servers and fought corruption issues and scrubs hanging the system more times than I can count. (This was within the last 24 months.) I was told by certain mailing lists, that btrfs isn't considered production level. So, I scrapped the lot, went to xfs and haven't had a problem since. I'm not sure why you'd want your mail spool on a filesystem and seems to hate being hammered with reads/writes. Personally, on all my mail spools, I use XFS or EXT4. OUr servers here handle 600million messages a month without trouble on those filesystems. Just my $0.02. Btrfs appears rather useful because the disks are SSDs, because it allows me to create subvolumes and because it handles SSDs nicely. Unfortunately, the SSDs are not suited for hardware RAID. The only alternative I know is xfs or ext4 on mdadm and no subvolumes, and md RAID has severe performance penalties which I´m not willing to afford. Part of the data I plan to store on these SSDs greatly benefits from the low latency, making things about 20--30 times faster for an important application. So what should I do? ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
[CentOS] intel wireless 3165 and CentOS 7.3
I am trying to get wireless working on CentOS 7.3 with intel wireless 3165 ip link 1: lo: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000 link/ether b8:ae:ed:77:b3:3a brd ff:ff:ff:ff:ff:ff 3: wlan0: mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000 link/ether 34:02:86:cc:a0:79 brd ff:ff:ff:ff:ff:ff 4: virbr0: mtu 1500 qdisc noqueue state DOWN mode DEFAULT qlen 1000 link/ether 52:54:00:70:8f:48 brd ff:ff:ff:ff:ff:ff 5: virbr0-nic: mtu 1500 qdisc noqueue master virbr0 state DOWN mode DEFAULT qlen 500 link/ether 52:54:00:70:8f:48 brd ff:ff:ff:ff:ff:ff lspci 00:00.0 Host bridge: Intel Corporation Device 2280 (rev 21) 00:02.0 VGA compatible controller: Intel Corporation Device 22b1 (rev 21) 00:13.0 SATA controller: Intel Corporation Device 22a3 (rev 21) 00:14.0 USB controller: Intel Corporation Device 22b5 (rev 21) 00:1a.0 Encryption controller: Intel Corporation Device 2298 (rev 21) 00:1b.0 Audio device: Intel Corporation Device 2284 (rev 21) 00:1c.0 PCI bridge: Intel Corporation Device 22c8 (rev 21) 00:1c.1 PCI bridge: Intel Corporation Device 22ca (rev 21) 00:1c.2 PCI bridge: Intel Corporation Device 22cc (rev 21) 00:1f.0 ISA bridge: Intel Corporation Device 229c (rev 21) 00:1f.3 SMBus: Intel Corporation Device 2292 (rev 21) 02:00.0 Network controller: Intel Corporation Wireless 3165 (rev 81) 03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15) I have created the ifcfg-ESSID and keys-ESSID files. but I dont even thing the wireless is loading. ifconfig does not report wlan0 or anything. What am I missing to get wireless going? Thanks, Jerry ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
I think it depends on who you ask. Facebook and Netflix are using it extensively in production: https://www.linux.com/news/learn/intro-to-linux/how-facebook-uses-linux-and-btrfs-interview-chris-mason Though they have the in-house kernel engineering resources to troubleshoot problems. When I see quotes like this [1] on the product's WIKI: "The parity RAID code has multiple serious data-loss bugs in it. It should not be used for anything other than testing purposes." I'm reluctant to store anything of value on it. Have you considered using ZoL? I've been using it for quite some time and haven't lost data. - Ryan http://prefetch.net [1] https://btrfs.wiki.kernel.org/index.php/RAID56 On Thu, Sep 7, 2017 at 2:12 PM, Mark Haney wrote: > On 09/07/2017 01:57 PM, hw wrote: >> >> >> Hi, >> >> is there anything that speaks against putting a cyrus mail spool onto a >> btrfs subvolume? >> > I might be the lone voice on this, but I refuse to use btrfs for anything, > much less a mail spool. I used it in production on DB and Web servers and > fought corruption issues and scrubs hanging the system more times than I can > count. (This was within the last 24 months.) I was told by certain mailing > lists, that btrfs isn't considered production level. So, I scrapped the > lot, went to xfs and haven't had a problem since. > > I'm not sure why you'd want your mail spool on a filesystem and seems to > hate being hammered with reads/writes. Personally, on all my mail spools, I > use XFS or EXT4. OUr servers here handle 600million messages a month > without trouble on those filesystems. > > Just my $0.02. > -- > > Mark Haney > Network Engineer at NeoNova > 919-460-3330 option 1 > mark.ha...@neonova.net > www.neonova.net > > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
I hate top posting, but since you've got two items I want to comment on, I'll suck it up for now. Having SSDs alone will give you great performance regardless of filesystem. BTRFS isn't going to impact I/O any more significantly than, say, XFS. It does have serious stability/data integrity issues that XFS doesn't have. There's no reason not to use SSDs for storage of immediate data and mechanical drives for archival data storage. As for VMs we run a huge Zimbra cluster in VMs on VPC with large primary SSD volumes and even larger (and slower) secondary volumes for archived mail. It's all CentOS 6 and works very well. We process 600 million emails a month on that virtual cluster. All EXT4 inside LVM. I can't tell you what to do, but it seems to me you're viewing your setup from a narrow SSD/BTRFS standpoint. Lots of ways to skin that cat. On 09/08/2017 08:07 AM, hw wrote: PS: What kind of storage solutions do people use for cyrus mail spools? Apparently you can not use remote storage, at least not NFS. That even makes it difficult to use a VM due to limitations of available disk space. I´m reluctant to use btrfs, but there doesn´t seem to be any reasonable alternative. hw wrote: Mark Haney wrote: On 09/07/2017 01:57 PM, hw wrote: Hi, is there anything that speaks against putting a cyrus mail spool onto a btrfs subvolume? I might be the lone voice on this, but I refuse to use btrfs for anything, much less a mail spool. I used it in production on DB and Web servers and fought corruption issues and scrubs hanging the system more times than I can count. (This was within the last 24 months.) I was told by certain mailing lists, that btrfs isn't considered production level. So, I scrapped the lot, went to xfs and haven't had a problem since. I'm not sure why you'd want your mail spool on a filesystem and seems to hate being hammered with reads/writes. Personally, on all my mail spools, I use XFS or EXT4. OUr servers here handle 600million messages a month without trouble on those filesystems. Just my $0.02. Btrfs appears rather useful because the disks are SSDs, because it allows me to create subvolumes and because it handles SSDs nicely. Unfortunately, the SSDs are not suited for hardware RAID. The only alternative I know is xfs or ext4 on mdadm and no subvolumes, and md RAID has severe performance penalties which I´m not willing to afford. Part of the data I plan to store on these SSDs greatly benefits from the low latency, making things about 20--30 times faster for an important application. So what should I do? -- Mark Haney Network Engineer at NeoNova 919-460-3330 option 1 mark.ha...@neonova.net www.neonova.net ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
Matty wrote: I think it depends on who you ask. Facebook and Netflix are using it extensively in production: https://www.linux.com/news/learn/intro-to-linux/how-facebook-uses-linux-and-btrfs-interview-chris-mason Though they have the in-house kernel engineering resources to troubleshoot problems. When I see quotes like this [1] on the product's WIKI: "The parity RAID code has multiple serious data-loss bugs in it. It should not be used for anything other than testing purposes." It´s RAID1, not 5/6. It´s only 2 SSDs. I do not /need/ to put the mail spool there, but it makes sense because the data that benefits from the low latency fills about only 5% of them, and the spool is mostly read, resulting in not so much wear of the SSDs. I can probably do a test with that data on the hardware RAID, and if performance is comparable, I rather put it there than on the SSDs. I'm reluctant to store anything of value on it. Have you considered using ZoL? I've been using it for quite some time and haven't lost data. Yes, and I´m moving away from ZFS because it remains alien, and the performance is poor. ZFS wasn´t designed with performance in mind, and that shows. It is amazing that SSDs with Linux are still so pointless and that there is no file system available actually suited for production use providing features ZFS and btrfs are valued for. It´s even frustrating that disk access still continues to defeat performance so much. Maybe it´s crazy wanting to put data onto SSDs with btrfs because the hardware RAID is also RAID1, for performance and better resistance against failures than RAID5 has. I guess I really shouldn´t do that. Now I´m looking forward to the test with the hardware RAID. A RAID1 of 8 disks may yield even better performance than 2 SSDs in software RAID1 with btrfs. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
Mark Haney wrote: I hate top posting, but since you've got two items I want to comment on, I'll suck it up for now. I do, too, yet sometimes it´s reasonable. I also hate it when the lines are too long :) Having SSDs alone will give you great performance regardless of filesystem. It depends, i. e. I can´t tell how these SSDs would behave if large amounts of data would be written and/or read to/from them over extended periods of time because I haven´t tested that. That isn´t the application, anyway. BTRFS isn't going to impact I/O any more significantly than, say, XFS. But mdadm does, the impact is severe. I know there are ppl saying otherwise, but I´ve seen the impact myself, and I definitely don´t want it on that particular server because it would likely interfere with other services. I don´t know if the software RAID of btrfs is better in that or not, though, but I´m seeing btrfs on SSDs being fast, and testing with the particular application has shown a speedup of factor 20--30. That is the crucial improvement. If the hardware RAID delivers that, I´ll use that and probably remove the SSDs from the machine as it wouldn´t even make sense to put temporary data onto them because that would involve software RAID. It does have serious stability/data integrity issues that XFS doesn't have. There's no reason not to use SSDs for storage of immediate data and mechanical drives for archival data storage. As for VMs we run a huge Zimbra cluster in VMs on VPC with large primary SSD volumes and even larger (and slower) secondary volumes for archived mail. It's all CentOS 6 and works very well. We process 600 million emails a month on that virtual cluster. All EXT4 inside LVM. Do you use hardware RAID with SSDs? I can't tell you what to do, but it seems to me you're viewing your setup from a narrow SSD/BTRFS standpoint. Lots of ways to skin that cat. That´s because I do not store data on a single disk, without redundancy, and the SSDs I have are not suitable for hardware RAID. So what else is there but either md-RAID or btrfs when I do not want to use ZFS? I also do not want to use md-RAID, hence only btrfs remains. I also like to use sub-volumes, though that isn´t a requirement (because I can use directories instead and loose the ability to make snapshots). I stay away from LVM because that just sucks. It wouldn´t even have any advantage in this case. On 09/08/2017 08:07 AM, hw wrote: PS: What kind of storage solutions do people use for cyrus mail spools? Apparently you can not use remote storage, at least not NFS. That even makes it difficult to use a VM due to limitations of available disk space. I´m reluctant to use btrfs, but there doesn´t seem to be any reasonable alternative. hw wrote: Mark Haney wrote: On 09/07/2017 01:57 PM, hw wrote: Hi, is there anything that speaks against putting a cyrus mail spool onto a btrfs subvolume? I might be the lone voice on this, but I refuse to use btrfs for anything, much less a mail spool. I used it in production on DB and Web servers and fought corruption issues and scrubs hanging the system more times than I can count. (This was within the last 24 months.) I was told by certain mailing lists, that btrfs isn't considered production level. So, I scrapped the lot, went to xfs and haven't had a problem since. I'm not sure why you'd want your mail spool on a filesystem and seems to hate being hammered with reads/writes. Personally, on all my mail spools, I use XFS or EXT4. OUr servers here handle 600million messages a month without trouble on those filesystems. Just my $0.02. Btrfs appears rather useful because the disks are SSDs, because it allows me to create subvolumes and because it handles SSDs nicely. Unfortunately, the SSDs are not suited for hardware RAID. The only alternative I know is xfs or ext4 on mdadm and no subvolumes, and md RAID has severe performance penalties which I´m not willing to afford. Part of the data I plan to store on these SSDs greatly benefits from the low latency, making things about 20--30 times faster for an important application. So what should I do? ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] login case sensitivity
On Thu, September 7, 2017 14:07, hw wrote: > Gordon Messmer wrote: >> On 09/07/2017 08:11 AM, Stephen John Smoogen wrote: >>> This was always problematic because DNS hostnames and >>> email addresses in the RFC standards were case insensitive >> >> >> Not quite. SMTP is required to treat the "local-part" of the RCPT >> argument as case-sensitive, and to preserve case when relaying mail. >> The destination is allowed to treat addresses according to local >> policy, but in general SMTP is case sensitive with regard to the >> user identifier. > > Last time I checked, RFCs said that local parts *should not* be case > sensitive, and cyrus defaulted to treat them case sensitive, which > is a default that usually needs to be changed because senders of > messages tend to not pay any attention to the case sensitiveness > of recipient addresses at all, which then confuses them like any > other error. > > https://tools.ietf.org/html/rfc5321 Updated by: 7504DRAFT STANDARD Errata Exist Network Working Group J. Klensin Request for Comments: 5321October 2008 Obsoletes: 2821 Updates: 1123 Category: Standards Track . . . 2.4. General Syntax Principles and Transaction Model . . . Verbs and argument values (e.g., "TO:" or "to:" in the RCPT command and extension name keywords) are not case sensitive, with the sole exception in this specification of a mailbox local-part (SMTP Extensions may explicitly specify case-sensitive elements). That is, a command verb, an argument value other than a mailbox local-part, and free form text MAY be encoded in upper case, lower case, or any mixture of upper and lower case with no impact on its meaning. __The local-part of a mailbox MUST BE treated as case sensitive.__ Therefore, SMTP implementations MUST take care to preserve the case of mailbox local-parts. In particular, for some hosts, the user "smith" is different from the user "Smith". However, exploiting the case sensitivity of mailbox local-parts impedes interoperability and is discouraged. Mailbox domains follow normal DNS rules and are hence not case sensitive. . . . Case munging of the local part is handled by the local delivery agent in my experience. The Cyrus LMTP service can be, and often is, configured to force lower case munging (imapd.conf 'lmtp_downcase_rcpt: 1') of the local part. That decision is site specific. -- *** e-Mail is NOT a SECURE channel *** Do NOT transmit sensitive data via e-Mail Do NOT open attachments nor follow links sent by e-Mail James B. Byrnemailto:byrn...@harte-lyne.ca Harte & Lyne Limited http://www.harte-lyne.ca 9 Brockley Drive vox: +1 905 561 1241 Hamilton, Ontario fax: +1 905 561 0757 Canada L8E 3C3 ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
hw wrote: > Mark Haney wrote: >> BTRFS isn't going to impact I/O any more significantly than, say, XFS. > > But mdadm does, the impact is severe. I know there are ppl saying > otherwise, but I´ve seen the impact myself, and I definitely don´t want > it on that particular server because it would likely interfere with > other services. I haven't really been following this thread, but if your requirements are that heavy, you're past the point that you need to spring some money and buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought them more recently? mark ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
m.r...@5-cent.us wrote: hw wrote: Mark Haney wrote: BTRFS isn't going to impact I/O any more significantly than, say, XFS. But mdadm does, the impact is severe. I know there are ppl saying otherwise, but I´ve seen the impact myself, and I definitely don´t want it on that particular server because it would likely interfere with other services. I haven't really been following this thread, but if your requirements are that heavy, you're past the point that you need to spring some money and buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought them more recently? Heavy requirements are not required for the impact of md-RAID to be noticeable. Hardware RAID is already in place, but the SSDs are "extra" and, as I said, not suited to be used with hardware RAID. It remains to be tested how the hardware RAID performs, which may be even better than the SSDs. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On 09/08/2017 09:49 AM, hw wrote: Mark Haney wrote: I hate top posting, but since you've got two items I want to comment on, I'll suck it up for now. I do, too, yet sometimes it´s reasonable. I also hate it when the lines are too long :) I'm afraid you'll have to live with it a bit longer. Sorry. Having SSDs alone will give you great performance regardless of filesystem. It depends, i. e. I can´t tell how these SSDs would behave if large amounts of data would be written and/or read to/from them over extended periods of time because I haven´t tested that. That isn´t the application, anyway. If your I/O is going to be heavy (and you've not mentioned expected traffic, so we can only go on what little we glean from your posts), then SSDs will likely start having issues sooner than a mechanical drive might. (Though, YMMV.) As I've said, we process 600 million messages a month, on primary SSDs in a VMWare cluster, with mechanical storage for older, archived user mail. Archived, may not be exactly correct, but the context should be clear. BTRFS isn't going to impact I/O any more significantly than, say, XFS. But mdadm does, the impact is severe. I know there are ppl saying otherwise, but I´ve seen the impact myself, and I definitely don´t want it on that particular server because it would likely interfere with other services. I don´t know if the software RAID of btrfs is better in that or not, though, but I´m seeing btrfs on SSDs being fast, and testing with the particular application has shown a speedup of factor 20--30. I never said anything about MD RAID. I trust that about as far as I could throw it. And having had 5 surgeries on my throwing shoulder wouldn't be far. That is the crucial improvement. If the hardware RAID delivers that, I´ll use that and probably remove the SSDs from the machine as it wouldn´t even make sense to put temporary data onto them because that would involve software RAID. Again, if the idea is to have fast primary storage, there are pretty large SSDs available now and I've hardware RAIDED SSDs before without trouble, though not for any heavy lifting, it's my test servers at home. Without an idea of the expected mail traffic, this is all speculation. It does have serious stability/data integrity issues that XFS doesn't have. There's no reason not to use SSDs for storage of immediate data and mechanical drives for archival data storage. As for VMs we run a huge Zimbra cluster in VMs on VPC with large primary SSD volumes and even larger (and slower) secondary volumes for archived mail. It's all CentOS 6 and works very well. We process 600 million emails a month on that virtual cluster. All EXT4 inside LVM. Do you use hardware RAID with SSDs? We do not here where I work, but that was setup LONG before I arrived. I can't tell you what to do, but it seems to me you're viewing your setup from a narrow SSD/BTRFS standpoint. Lots of ways to skin that cat. That´s because I do not store data on a single disk, without redundancy, and the SSDs I have are not suitable for hardware RAID. So what else is there but either md-RAID or btrfs when I do not want to use ZFS? I also do not want to use md-RAID, hence only btrfs remains. I also like to use sub-volumes, though that isn´t a requirement (because I can use directories instead and loose the ability to make snapshots). If the SSDs you have aren't suitable for hardware RAID, then they aren't good for production level mail spools, IMHO. I mean, you're talking like you're expecting a metric buttload of mail traffic, so it stands to reason you'll need really beefy hardware. I don't think you can do what you seem to need on budget hardware. Personally, and solely based on this thread alone, if I was building this in-house, I'd get a decent server cluster together and build a FC or iSCSI SAN to a Nimble storage array with Flash/SSD front ends and large HDDs in the back end. This solves virtually all your problems. The servers will have tiny SSD boot drives (which I prefer over booting from the SAN) and then everything else gets handled by the storage back-end. In effect this is how our mail servers are setup here. And they are virtual. I stay away from LVM because that just sucks. It wouldn´t even have any advantage in this case. LVM is a joke. It's always been something I've avoided like the plague. On 09/08/2017 08:07 AM, hw wrote: PS: What kind of storage solutions do people use for cyrus mail spools? Apparently you can not use remote storage, at least not NFS. That even makes it difficult to use a VM due to limitations of available disk space. I´m reluctant to use btrfs, but there doesn´t seem to be any reasonable alternative. hw wrote: Mark Haney wrote: On 09/07/2017 01:57 PM, hw wrote: Hi, is there anything that speaks against putting a cyrus mail spool onto a btrfs subvolume? I might be the lone voice on thi
Re: [CentOS] cyrus spool on btrfs?
On Fri, September 8, 2017 9:48 am, hw wrote: > m.r...@5-cent.us wrote: >> hw wrote: >>> Mark Haney wrote: >> BTRFS isn't going to impact I/O any more significantly than, say, XFS. >>> >>> But mdadm does, the impact is severe. I know there are ppl saying >>> otherwise, but I´ve seen the impact myself, and I definitely don´t >>> want >>> it on that particular server because it would likely interfere with >>> other services. >> >> I haven't really been following this thread, but if your requirements >> are >> that heavy, you're past the point that you need to spring some money and >> buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought them >> more recently? > > Heavy requirements are not required for the impact of md-RAID to be > noticeable. > > Hardware RAID is already in place, but the SSDs are "extra" and, as I > said, > not suited to be used with hardware RAID. Could someone, please, elaborate on the statement that "SSDs are not suitable for hardware RAID". Thanks. Valeri > > It remains to be tested how the hardware RAID performs, which may be even > better than the SSDs. > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos > Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On 8 September 2017 at 11:00, Valeri Galtsev wrote: > > On Fri, September 8, 2017 9:48 am, hw wrote: >> m.r...@5-cent.us wrote: >>> hw wrote: Mark Haney wrote: >>> > BTRFS isn't going to impact I/O any more significantly than, say, XFS. But mdadm does, the impact is severe. I know there are ppl saying otherwise, but I´ve seen the impact myself, and I definitely don´t want it on that particular server because it would likely interfere with other services. >>> >>> I haven't really been following this thread, but if your requirements >>> are >>> that heavy, you're past the point that you need to spring some money and >>> buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought them >>> more recently? >> >> Heavy requirements are not required for the impact of md-RAID to be >> noticeable. >> >> Hardware RAID is already in place, but the SSDs are "extra" and, as I >> said, >> not suited to be used with hardware RAID. > > Could someone, please, elaborate on the statement that "SSDs are not > suitable for hardware RAID". > It will depend on the type of SSD and the type of hardware RAID. There are at least 4 different classes of SSD drives with different levels of cache, write/read performance, number of lifetime writes, etc. There are also multiple types of hardware RAID. A lot of hardware RAID will try to even out disk usage in different ways. This means 'moving' the heavily used data from slow parts to fast parts etc etc. On an SSD all these extra writes aren't needed and so if the hardware RAID doesn't know about SSD technology it will wear out the SSD quickly. Other hardware raid parts that can cause faster failures on SSD's are where it does test writes all the time to see if disks are bad etc. Again if you have gone with commodity SSD's this will wear out the drive faster than expected and boom bad disks. That said, some hardware RAID's are supposedly made to work with SSD drive technology. They don't do those extra writes, they also assume that the disks underneath will read/write in near constant time so queueing of data is done differently. However that stuff costs extra money and not usually shipped in standard OEM hardware. > Thanks. > Valeri > >> >> It remains to be tested how the hardware RAID performs, which may be even >> better than the SSDs. >> ___ >> CentOS mailing list >> CentOS@centos.org >> https://lists.centos.org/mailman/listinfo/centos >> > > > > Valeri Galtsev > Sr System Administrator > Department of Astronomy and Astrophysics > Kavli Institute for Cosmological Physics > University of Chicago > Phone: 773-702-4247 > > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos -- Stephen J Smoogen. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On Fri, September 8, 2017 11:07 am, Stephen John Smoogen wrote: > On 8 September 2017 at 11:00, Valeri Galtsev > wrote: >> >> On Fri, September 8, 2017 9:48 am, hw wrote: >>> m.r...@5-cent.us wrote: hw wrote: > Mark Haney wrote: >> BTRFS isn't going to impact I/O any more significantly than, say, >> XFS. > > But mdadm does, the impact is severe. I know there are ppl saying > otherwise, but Iôve seen the impact myself, and I definitely > donôt > want > it on that particular server because it would likely interfere with > other services. I haven't really been following this thread, but if your requirements are that heavy, you're past the point that you need to spring some money and buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought them more recently? >>> >>> Heavy requirements are not required for the impact of md-RAID to be >>> noticeable. >>> >>> Hardware RAID is already in place, but the SSDs are "extra" and, as I >>> said, >>> not suited to be used with hardware RAID. >> >> Could someone, please, elaborate on the statement that "SSDs are not >> suitable for hardware RAID". >> > > It will depend on the type of SSD and the type of hardware RAID. There > are at least 4 different classes of SSD drives with different levels > of cache, write/read performance, number of lifetime writes, etc. > There are also multiple types of hardware RAID. A lot of hardware RAID > will try to even out disk usage in different ways. This means 'moving' > the heavily used data from slow parts to fast parts etc etc. Wow, you learn something every day ;-) Which hardware RAIDs do these moving of data (manufacturer/model, please - believe it or not I never heard of that ;-). And "slow part" and "fast part" of what are data being moved between? Thanks in advance for tutorial! Valeri > On an SSD > all these extra writes aren't needed and so if the hardware RAID > doesn't know about SSD technology it will wear out the SSD quickly. > Other hardware raid parts that can cause faster failures on SSD's are > where it does test writes all the time to see if disks are bad etc. > Again if you have gone with commodity SSD's this will wear out the > drive faster than expected and boom bad disks. > > That said, some hardware RAID's are supposedly made to work with SSD > drive technology. They don't do those extra writes, they also assume > that the disks underneath will read/write in near constant time so > queueing of data is done differently. However that stuff costs extra > money and not usually shipped in standard OEM hardware. > > >> Thanks. >> Valeri >> >>> >>> It remains to be tested how the hardware RAID performs, which may be >>> even >>> better than the SSDs. >>> ___ >>> CentOS mailing list >>> CentOS@centos.org >>> https://lists.centos.org/mailman/listinfo/centos >>> >> >> >> >> Valeri Galtsev >> Sr System Administrator >> Department of Astronomy and Astrophysics >> Kavli Institute for Cosmological Physics >> University of Chicago >> Phone: 773-702-4247 >> >> ___ >> CentOS mailing list >> CentOS@centos.org >> https://lists.centos.org/mailman/listinfo/centos > > > > -- > Stephen J Smoogen. > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos > Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On 8 September 2017 at 12:13, Valeri Galtsev wrote: > > On Fri, September 8, 2017 11:07 am, Stephen John Smoogen wrote: >> On 8 September 2017 at 11:00, Valeri Galtsev >> wrote: >>> >>> On Fri, September 8, 2017 9:48 am, hw wrote: m.r...@5-cent.us wrote: > hw wrote: >> Mark Haney wrote: > >>> BTRFS isn't going to impact I/O any more significantly than, say, >>> XFS. >> >> But mdadm does, the impact is severe. I know there are ppl saying >> otherwise, but I´ve seen the impact myself, and I definitely >> don´t >> want >> it on that particular server because it would likely interfere with >> other services. > > I haven't really been following this thread, but if your requirements > are > that heavy, you're past the point that you need to spring some money > and > buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought > them > more recently? Heavy requirements are not required for the impact of md-RAID to be noticeable. Hardware RAID is already in place, but the SSDs are "extra" and, as I said, not suited to be used with hardware RAID. >>> >>> Could someone, please, elaborate on the statement that "SSDs are not >>> suitable for hardware RAID". >>> >> >> It will depend on the type of SSD and the type of hardware RAID. There >> are at least 4 different classes of SSD drives with different levels >> of cache, write/read performance, number of lifetime writes, etc. >> There are also multiple types of hardware RAID. A lot of hardware RAID >> will try to even out disk usage in different ways. This means 'moving' >> the heavily used data from slow parts to fast parts etc etc. > > Wow, you learn something every day ;-) Which hardware RAIDs do these > moving of data (manufacturer/model, please - believe it or not I never > heard of that ;-). And "slow part" and "fast part" of what are data being > moved between? > > Thanks in advance for tutorial! > I thought it was HP who had these, but I can't find it.. which means without references... I get an F. My apologies on that. Thank you for keeping me honest. -- Stephen J Smoogen. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
Mark Haney wrote: On 09/08/2017 09:49 AM, hw wrote: Mark Haney wrote: I hate top posting, but since you've got two items I want to comment on, I'll suck it up for now. I do, too, yet sometimes it´s reasonable. I also hate it when the lines are too long :) I'm afraid you'll have to live with it a bit longer. Sorry. Having SSDs alone will give you great performance regardless of filesystem. It depends, i. e. I can´t tell how these SSDs would behave if large amounts of data would be written and/or read to/from them over extended periods of time because I haven´t tested that. That isn´t the application, anyway. If your I/O is going to be heavy (and you've not mentioned expected traffic, so we can only go on what little we glean from your posts), then SSDs will likely start having issues sooner than a mechanical drive might. (Though, YMMV.) As I've said, we process 600 million messages a month, on primary SSDs in a VMWare cluster, with mechanical storage for older, archived user mail. Archived, may not be exactly correct, but the context should be clear. I/O is not heavy in that sense, that´s why I said that´s not the application. There is I/O which, as tests have shown, benefits greatly from low latency, which is where the idea to use SSDs for the relevant data has arisen from. This I/O only involves a small amount of data and is not sustained over long periods of time. What exactly the problem is with the application being slow with spinning disks is unknown because I don´t have the sources, and the maker of the application refuses to deal with the problem entirely. Since the data requiring low latency will occupy about 5% of the available space on the SSDs and since they are large enough to hold the mail spool for about 10 years at its current rate of growth besides that data, these SSDs could be well used to hold that mail spool. BTRFS isn't going to impact I/O any more significantly than, say, XFS. But mdadm does, the impact is severe. I know there are ppl saying otherwise, but I´ve seen the impact myself, and I definitely don´t want it on that particular server because it would likely interfere with other services. I don´t know if the software RAID of btrfs is better in that or not, though, but I´m seeing btrfs on SSDs being fast, and testing with the particular application has shown a speedup of factor 20--30. I never said anything about MD RAID. I trust that about as far as I could throw it. And having had 5 surgeries on my throwing shoulder wouldn't be far. How else would I create a RAID with these SSDs? I´ve been using md-RAID for years, and it always worked fine. That is the crucial improvement. If the hardware RAID delivers that, I´ll use that and probably remove the SSDs from the machine as it wouldn´t even make sense to put temporary data onto them because that would involve software RAID. Again, if the idea is to have fast primary storage, there are pretty large SSDs available now and I've hardware RAIDED SSDs before without trouble, though not for any heavy lifting, it's my test servers at home. Without an idea of the expected mail traffic, this is all speculation. The SSDs don´t need to be large, and they aren´t. They are already greatly oversized at 512GB nominal capacity. There´s only a few hundred emails per day. There is no special requirement for their storage, but there is a lot of free space on these SSDs, and since the email traffic is mostly read-only, it won´t wear out the SSDs. It simply would make sense to put the mail spool onto these SSDs. It does have serious stability/data integrity issues that XFS doesn't have. There's no reason not to use SSDs for storage of immediate data and mechanical drives for archival data storage. As for VMs we run a huge Zimbra cluster in VMs on VPC with large primary SSD volumes and even larger (and slower) secondary volumes for archived mail. It's all CentOS 6 and works very well. We process 600 million emails a month on that virtual cluster. All EXT4 inside LVM. Do you use hardware RAID with SSDs? We do not here where I work, but that was setup LONG before I arrived. Probably with the very expensive SSDs suited for this ... I can't tell you what to do, but it seems to me you're viewing your setup from a narrow SSD/BTRFS standpoint. Lots of ways to skin that cat. That´s because I do not store data on a single disk, without redundancy, and the SSDs I have are not suitable for hardware RAID. So what else is there but either md-RAID or btrfs when I do not want to use ZFS? I also do not want to use md-RAID, hence only btrfs remains. I also like to use sub-volumes, though that isn´t a requirement (because I can use directories instead and loose the ability to make snapshots). If the SSDs you have aren't suitable for hardware RAID, then they aren't good for production level mail spools, IMHO. I mean, you're talking like you're expecting a metric buttload o
Re: [CentOS] cyrus spool on btrfs?
Mark Haney wrote: > On 09/08/2017 09:49 AM, hw wrote: >> Mark Haney wrote: >> >> It depends, i. e. I can´t tell how these SSDs would behave if large >> amounts of data would be written and/or read to/from them over extended >> periods of time because I haven´t tested that. That isn´t the >> application, anyway. > > If your I/O is going to be heavy (and you've not mentioned expected > traffic, so we can only go on what little we glean from your posts), > then SSDs will likely start having issues sooner than a mechanical drive > might. (Though, YMMV.) As I've said, we process 600 million messages a > month, on primary SSDs in a VMWare cluster, with mechanical storage for > older, archived user mail. Archived, may not be exactly correct, but > the context should be clear. > One thing to note, which I'm aware of because I was recently spec'ing out a Dell server: Dell, at least, offers two kinds of SSDs, one for heavy write, I think it was, and one for equal r/w. You might dig into that. >> >> But mdadm does, the impact is severe. I know there are ppl saying >> otherwise, but I´ve seen the impact myself, and I definitely don´t want >> it on that particular server because it would likely interfere with other >> services. I don´t know if the software RAID of btrfs is better in that >> or not, though, but I´m seeing btrfs on SSDs being fast, and testing >> with the particular application has shown a speedup of factor 20--30. Odd, we've never seen anything like that. Of course, we're not handling the kind of mail you are... but serious scientific computing hits storage hard, also. > I never said anything about MD RAID. I trust that about as far as I > could throw it. And having had 5 surgeries on my throwing shoulder > wouldn't be far. Why? We have it all over, and have never seen a problem with it. Nor have I, personally, as I have a RAID 1 at home. mark ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
Valeri Galtsev wrote: On Fri, September 8, 2017 9:48 am, hw wrote: m.r...@5-cent.us wrote: hw wrote: Mark Haney wrote: BTRFS isn't going to impact I/O any more significantly than, say, XFS. But mdadm does, the impact is severe. I know there are ppl saying otherwise, but I´ve seen the impact myself, and I definitely don´t want it on that particular server because it would likely interfere with other services. I haven't really been following this thread, but if your requirements are that heavy, you're past the point that you need to spring some money and buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought them more recently? Heavy requirements are not required for the impact of md-RAID to be noticeable. Hardware RAID is already in place, but the SSDs are "extra" and, as I said, not suited to be used with hardware RAID. Could someone, please, elaborate on the statement that "SSDs are not suitable for hardware RAID". When you search for it, you´ll find that besides wearing out undesirably fast --- which apparently can be contributed mostly to less overcommitment of the drive --- you may also experience degraded performance over time which can be worse than you would get with spinning disks, or at least not much better. Add to that the firmware being designed for an entirely different application and having bugs, and your experiences with surprisingly incompatible hardware, and you can imagine that using an SSD not designed for hardware RAID applications with hardware RAID is a bad idea. There is a difference like night and day between "consumer hardware" and hardware you can actually use, and that is not only the price you pay for it. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
hw wrote: > Mark Haney wrote: >> On 09/08/2017 09:49 AM, hw wrote: >>> Mark Haney wrote: > Probably with the very expensive SSDs suited for this ... >>> >>> That´s because I do not store data on a single disk, without >>> redundancy, and the SSDs I have are not suitable for hardware RAID. That's a biggie: are these SSDs consumer grade, or enterprise grade? It was common knowledge 8-9 years ago that you *never* want consumer grade in anything that mattered, other than maybe a home PC - they wear out much sooner. But then, you can't really use consumer grade h/ds in a server. We like the NAS-rated ones, like WD Red, which are about 1.33% the price of consumer grade, and solid... and a lot less than the enterprise-grade, which are about 3x consumer grade. mark ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
m.r...@5-cent.us wrote: Mark Haney wrote: On 09/08/2017 09:49 AM, hw wrote: Mark Haney wrote: It depends, i. e. I can´t tell how these SSDs would behave if large amounts of data would be written and/or read to/from them over extended periods of time because I haven´t tested that. That isn´t the application, anyway. If your I/O is going to be heavy (and you've not mentioned expected traffic, so we can only go on what little we glean from your posts), then SSDs will likely start having issues sooner than a mechanical drive might. (Though, YMMV.) As I've said, we process 600 million messages a month, on primary SSDs in a VMWare cluster, with mechanical storage for older, archived user mail. Archived, may not be exactly correct, but the context should be clear. One thing to note, which I'm aware of because I was recently spec'ing out a Dell server: Dell, at least, offers two kinds of SSDs, one for heavy write, I think it was, and one for equal r/w. You might dig into that. But mdadm does, the impact is severe. I know there are ppl saying otherwise, but I´ve seen the impact myself, and I definitely don´t want it on that particular server because it would likely interfere with other services. I don´t know if the software RAID of btrfs is better in that or not, though, but I´m seeing btrfs on SSDs being fast, and testing with the particular application has shown a speedup of factor 20--30. Odd, we've never seen anything like that. Of course, we're not handling the kind of mail you are... but serious scientific computing hits storage hard, also. I never said anything about MD RAID. I trust that about as far as I could throw it. And having had 5 surgeries on my throwing shoulder wouldn't be far. Why? We have it all over, and have never seen a problem with it. Nor have I, personally, as I have a RAID 1 at home. Make a test and replace a software RAID5 with a hardware RAID5. Even with only 4 disks, you will see an overall performance gain. I´m guessing that the SATA controllers they put onto the mainboards are not designed to handle all the data --- which gets multiplied to all the disks --- and that the PCI bus might get clogged. There´s also the CPU being burdened with the calculations required for the RAID, and that may not be displayed by tools like top, so you can be fooled easily. Graphics cards have acceleration in hardware for a reason. What was the last time you tried to do software rendering, and what frame rates did you get? :) Offloading the I/O to a designated controller gives you room for the things you actually want to do, similar to a graphics card. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On 09/08/2017 01:31 PM, hw wrote: Mark Haney wrote: I/O is not heavy in that sense, that´s why I said that´s not the application. There is I/O which, as tests have shown, benefits greatly from low latency, which is where the idea to use SSDs for the relevant data has arisen from. This I/O only involves a small amount of data and is not sustained over long periods of time. What exactly the problem is with the application being slow with spinning disks is unknown because I don´t have the sources, and the maker of the application refuses to deal with the problem entirely. Since the data requiring low latency will occupy about 5% of the available space on the SSDs and since they are large enough to hold the mail spool for about 10 years at its current rate of growth besides that data, these SSDs could be well used to hold that mail spool. See, this is the kind of information that would have made this thread far shorter. (Maybe.) The one thing that you didn't explain is whether this application is the one /using/ the mail spool or if you're adding Cyrus to that system to be a mail server. BTRFS isn't going to impact I/O any more significantly than, say, XFS. But mdadm does, the impact is severe. I know there are ppl saying otherwise, but I´ve seen the impact myself, and I definitely don´t want it on that particular server because it would likely interfere with other services. I don´t know if the software RAID of btrfs is better in that or not, though, but I´m seeing btrfs on SSDs being fast, and testing with the particular application has shown a speedup of factor 20--30. I never said anything about MD RAID. I trust that about as far as I could throw it. And having had 5 surgeries on my throwing shoulder wouldn't be far. How else would I create a RAID with these SSDs? I´ve been using md-RAID for years, and it always worked fine. That is the crucial improvement. If the hardware RAID delivers that, I´ll use that and probably remove the SSDs from the machine as it wouldn´t even make sense to put temporary data onto them because that would involve software RAID. Again, if the idea is to have fast primary storage, there are pretty large SSDs available now and I've hardware RAIDED SSDs before without trouble, though not for any heavy lifting, it's my test servers at home. Without an idea of the expected mail traffic, this is all speculation. The SSDs don´t need to be large, and they aren´t. They are already greatly oversized at 512GB nominal capacity. There´s only a few hundred emails per day. There is no special requirement for their storage, but there is a lot of free space on these SSDs, and since the email traffic is mostly read-only, it won´t wear out the SSDs. It simply would make sense to put the mail spool onto these SSDs. It does have serious stability/data integrity issues that XFS doesn't have. There's no reason not to use SSDs for storage of immediate data and mechanical drives for archival data storage. As for VMs we run a huge Zimbra cluster in VMs on VPC with large primary SSD volumes and even larger (and slower) secondary volumes for archived mail. It's all CentOS 6 and works very well. We process 600 million emails a month on that virtual cluster. All EXT4 inside LVM. Do you use hardware RAID with SSDs? We do not here where I work, but that was setup LONG before I arrived. Probably with the very expensive SSDs suited for this ... Possibly, but that's somewhat irrelevant. I've taken off the shelf SSDs and hardware RAID'd them. If they work for the hell I put them through (processing weather data), they'll work for the type of service you're saying you have. If the SSDs you have aren't suitable for hardware RAID, then they aren't good for production level mail spools, IMHO. I mean, you're talking like you're expecting a metric buttload of mail traffic, so it stands to reason you'll need really beefy hardware. I don't think you can do what you seem to need on budget hardware. Personally, and solely based on this thread alone, if I was building this in-house, I'd get a decent server cluster together and build a FC or iSCSI SAN to a Nimble storage array with Flash/SSD front ends and large HDDs in the back end. This solves virtually all your problems. The servers will have tiny SSD boot drives (which I prefer over booting from the SAN) and then everything else gets handled by the storage back-end. If SSDs not suitable for RAID usage aren´t suitable for production use, then basically all SSDs not suitable for RAID usage are SSDs that can´t be used for anything that requires something less volatile than a ramdisk. Experience with such SSDs contradicts this so far. Not true at all. Maybe 5 years ago SSDs were hit or miss with hardware RAID. Not anymore. It's just another drive to the system, the controllers don't know the difference between a SATA HDD and a SATA SSD. Couple that with the low volume
Re: [CentOS] cyrus spool on btrfs?
Mark Haney wrote: > On 09/08/2017 01:31 PM, hw wrote: >> Mark Haney wrote: >> >> Probably with the very expensive SSDs suited for this ... > Possibly, but that's somewhat irrelevant. I've taken off the shelf SSDs > and hardware RAID'd them. If they work for the hell I put them through > (processing weather data), they'll work for the type of service you're > saying you have. > Not true at all. Maybe 5 years ago SSDs were hit or miss with hardware > RAID. Not anymore. It's just another drive to the system, the > controllers don't know the difference between a SATA HDD and a SATA SSD. > Couple that with the low volume of mail, and you should be fine for HW > RAID. Actually, with the usage you're talking about, I'm surprised you're using SATA and not SAS. mark ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On 09/07/2017 12:57 PM, hw wrote: > > Hi, > > is there anything that speaks against putting a cyrus mail spool onto a > btrfs subvolume? This is what Red Hat says about btrfs: The Btrfs file system has been in Technology Preview state since the initial release of Red Hat Enterprise Linux 6. Red Hat will not be moving Btrfs to a fully supported feature and it will be removed in a future major release of Red Hat Enterprise Linux. The Btrfs file system did receive numerous updates from the upstream in Red Hat Enterprise Linux 7.4 and will remain available in the Red Hat Enterprise Linux 7 series. However, this is the last planned update to this feature. signature.asc Description: OpenPGP digital signature ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On Fri, September 8, 2017 12:56 pm, hw wrote: > Valeri Galtsev wrote: >> >> On Fri, September 8, 2017 9:48 am, hw wrote: >>> m.r...@5-cent.us wrote: hw wrote: > Mark Haney wrote: >> BTRFS isn't going to impact I/O any more significantly than, say, >> XFS. > > But mdadm does, the impact is severe. I know there are ppl saying > otherwise, but Iôve seen the impact myself, and I definitely > donôt > want > it on that particular server because it would likely interfere with > other services. I haven't really been following this thread, but if your requirements are that heavy, you're past the point that you need to spring some money and buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought them more recently? >>> >>> Heavy requirements are not required for the impact of md-RAID to be >>> noticeable. >>> >>> Hardware RAID is already in place, but the SSDs are "extra" and, as I >>> said, >>> not suited to be used with hardware RAID. >> >> Could someone, please, elaborate on the statement that "SSDs are not >> suitable for hardware RAID". > > When you search for it, you´ll find that besides wearing out undesirably > fast --- which apparently can be contributed mostly to less overcommitment > of the drive --- you may also experience degraded performance over time > which can be worse than you would get with spinning disks, or at least not > much better. Thanks. That seems to clear fog a little bit. I still would like to hear manufacturers/models here. My choices would be: Areca or LSI (bought out by Intel, so former LSI chipset and microcode/firmware) and as SSD Samsung Evo SATA III. Does anyone who used these in hardware RAID can offer any bad experience description? I am kind of shying away from "crap" hardware which in a long run is more expensive, even though looks cheaper (Pricegrabber is your enemy - I would normally say to my users). So, I never would consider using poorly/cheaply designed hardware in some setup (e.g. hardware RAID based storage) one expects performance from. Am I still taking chance hitting "bad" hardware RAID + SSD combination? Just curious where we actually stand. Thanks again for fruitful discussion! Valeri > > Add to that the firmware being designed for an entirely different > application > and having bugs, and your experiences with surprisingly incompatible > hardware, > and you can imagine that using an SSD not designed for hardware RAID > applications with hardware RAID is a bad idea. There is a difference like > night and day between "consumer hardware" and hardware you can actually > use, > and that is not only the price you pay for it. > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos > Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On 9/8/2017 12:52 PM, Valeri Galtsev wrote: Thanks. That seems to clear fog a little bit. I still would like to hear manufacturers/models here. My choices would be: Areca or LSI (bought out by Intel, so former LSI chipset and microcode/firmware) and as SSD Samsung Evo SATA III. Does anyone who used these in hardware RAID can offer any bad experience description? Does the Samsung EVO have supercaps and write-back buffer protection? if not, it is in NO way suitable for reliable use in a raid/server environment. as far as raiding SSDs go, the ONLY raid I'd use with them is raid1 mirroring (or if more than 2, raid10 striped mirrors). And I'd probably do it with OS based software raid, as thats more likely to support SSD trim than a hardware raid card, plus allows the host to monitor the SSDs via SMART, which a hardware raid card probably hides. I'd also make sure I undercommit the size of the SSD, so if its a 500GB SSD, I'd make absolutely sure to never have more than 300-350GB of data on it. if its part of a stripe set, the only way to ensure this is to partition it so the raid slice is only 300-350GB. -- john r pierce, recycling bits in santa cruz ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On Fri, Sep 8, 2017 at 2:52 PM, Valeri Galtsev wrote: > > manufacturers/models here. My choices would be: Areca or LSI (bought out > by Intel, so former LSI chipset and microcode/firmware) and as SSD Samsung > Intel only purchased the networking component of LSI, Axxia, from Avago. The RAID division was merged into Broadcom (post Avago merger). ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On 09/08/2017 11:06 AM, hw wrote: Make a test and replace a software RAID5 with a hardware RAID5. Even with only 4 disks, you will see an overall performance gain. I´m guessing that the SATA controllers they put onto the mainboards are not designed to handle all the data --- which gets multiplied to all the disks --- and that the PCI bus might get clogged. There´s also the CPU being burdened with the calculations required for the RAID, and that may not be displayed by tools like top, so you can be fooled easily. That sounds like a whole lot of guesswork, which I'd suggest should inspire slightly less confidence than you are showing in it. RAID parity calculations are accounted under a process named md_raid. You will see time consumed by that code under all of the normal process accounting tools, including total time under "ps" and current time under "top". Typically, your CPU is vastly faster than the cheap processors on hardware RAID controllers, and the advantage will go to software RAID over hardware. If your system is CPU bound, however, and you need that extra fraction of a percent of CPU cycles that go to calculating parity, hardware might offer an advantage. The last system I purchased had its storage controller on a PCIe 3.0 x16 port, so its throughput to the card should be around 16GB/s. Yours might be different. I should be able to put roughly 20 disks on that card before the PCIe bus is the bottleneck. If this were a RAID6 volume, a hardware RAID card would be able to support sustained writes to 22 drives vs 20 for md RAID. I don't see that as a compelling advantage, but it is potentially an advantage for a hypothetical hardware RAID card. When you are testing your 4 disk RAID5 array, microbenchmarks like bonnie++ will show you a very significant advantage toward the hardware RAID as very small writes are added to the battery-backed cache on the card and the OS considers them complete. However, on many cards, if the system writes data to the card faster than the card writes to disks, the cache will fill up, and at that point, the system performance can suddenly and unexpectedly plummet. I've fun a few workloads where that happened, and we had to replace the system entirely, and use software RAID instead. Software RAID's performance tends to be far more predictable as the workload increases. Outside of microbenchmarks like bonnie++, software RAID often offers much better performance than hardware RAID controllers. Having tested systems extensively for many years, my advice is this: there is no simple answer to the question of whether software or hardware RAID is better. You need to test your specific application on your specific hardware to determine what configuration will work best. There are some workloads where a hardware controller will offer better write performance, since a battery backed write-cache can complete very small random writes very quickly. If that is not the specific behavior of your application, software RAID will very often offer you better performance, as well as other advantages. On the other hand, software RAID absolutely requires a monitored UPS and tested auto-shutdown in order to be remotely reliable, just as a hardware RAID controller requires a battery backed write-cache, and monitoring of the battery state. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On Fri, September 8, 2017 3:06 pm, John R Pierce wrote: > On 9/8/2017 12:52 PM, Valeri Galtsev wrote: >> Thanks. That seems to clear fog a little bit. I still would like to hear >> manufacturers/models here. My choices would be: Areca or LSI (bought out >> by Intel, so former LSI chipset and microcode/firmware) and as SSD >> Samsung >> Evo SATA III. Does anyone who used these in hardware RAID can offer any >> bad experience description? > > > Does the Samsung EVO have supercaps and write-back buffer protection? > if not, it is in NO way suitable for reliable use in a raid/server > environment. With all due respect, John, this is the same as hard drive cache is not backed up power wise for a case of power loss. And hard drives all lie about write operation completed before data actually are on the platters. So we can claim the same: hard drives are not suitable for RAID. I implied to find out from experts in what respect they claim SSDs are unsuitable for hardware RAID as opposed to mechanical hard drives. Am I missing something? > > as far as raiding SSDs go, the ONLY raid I'd use with them is raid1 > mirroring (or if more than 2, raid10 striped mirrors). And I'd probably > do it with OS based software raid, as thats more likely to support SSD > trim than a hardware raid card, plus allows the host to monitor the SSDs > via SMART, which a hardware raid card probably hides. Good, thanks. My 3ware RAIDs through their 3dm daemon do warn me about SMART status: fail (meaning the drive though working should according to SMART be replaced ASAP). Not certain off hand about LSI ones (one should be able to query them through command line client utility). > > I'd also make sure I undercommit the size of the SSD, so if its a 500GB > SSD, I'd make absolutely sure to never have more than 300-350GB of data > on it.  if its part of a stripe set, the only way to ensure this is to > partition it so the raid slice is only 300-350GB. Great point! And one may want to adjust stripe size to be resembling SSDs internals, as default is for hard drives, right? Thanks, John, that was instructive! Valeri > > > -- > john r pierce, recycling bits in santa cruz > > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos > Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] cyrus spool on btrfs?
On 9/8/2017 2:36 PM, Valeri Galtsev wrote: With all due respect, John, this is the same as hard drive cache is not backed up power wise for a case of power loss. And hard drives all lie about write operation completed before data actually are on the platters. So we can claim the same: hard drives are not suitable for RAID. I implied to find out from experts in what respect they claim SSDs are unsuitable for hardware RAID as opposed to mechanical hard drives. Am I missing something? major difference is, SSD's do a LOT more write buffering as their internal write blocks are on the order of a few 100KB, also they extensively reorder data on the media, both for wear leveling and to minimize physical block writes so there's really no way the host and/or controller can track whats going on. enterprise hard disks do NOT do hidden write buffering, its all fully managable via SAS or SATA commands. desktop drives tend to lie about it to achieve better performance. I do NOT use desktop drives in raids. ... And one may want to adjust stripe size to be resembling SSDs internals, as default is for hard drives, right? as the SSD physical data blocks have no visible relation to logical block numbers or CHS, its not practical to do this. I'd use a fairly large stripe size, like 1MB, so more data can be sequentially written to the same device (even tho the device will scramble it all over as it sees fit). -- john r pierce, recycling bits in santa cruz ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
[CentOS] CentOS 7 on PPC64le booting from a MD RAID volume
I've been trying to install CentOS 7 AltArch ppc64le onto a new Power 8 system and I want to configure mdraid for the volumes. I can get everything working if I install to a single disk, but when I configure for RAID 1, the system fails to boot. So, is mdraid1 supported for booting a Power 8 system? Tom Leach le...@coas.oregonstate.edu ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
