Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-07-02 Thread Wojciech Puchar
No, I'm saying you are trolling. A concat of RAID1 pairs has reliability identical to RAID10. not a concat but separate filesystem.

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-07-01 Thread Stan Hoeppner
On 7/1/2012 5:48 AM, Charles Marcus wrote: > On 2012-07-01 3:17 AM, Stan Hoeppner wrote: >> In a production environment, the mirror pairs will be duplexed across >> two SAS/SATA controllers. >> >> Duplexing the mirrors makes a concat/RAID1, and a properly configured >> RAID10, inherently more reli

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-07-01 Thread Charles Marcus
On 2012-07-01 3:17 AM, Stan Hoeppner wrote: In a production environment, the mirror pairs will be duplexed across two SAS/SATA controllers. Duplexing the mirrors makes a concat/RAID1, and a properly configured RAID10, inherently more reliable than RAID5 or RAID6, which simply can't be protected

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-07-01 Thread Charles Marcus
On 2012-06-29 12:07 PM, Ed W wrote: On 29/06/2012 12:15, Charles Marcus wrote: Depends on what you mean exactly by 'incorrect'... I'm sorry, this wasn't meant to be an attack on you, No worries - it wasn't taken that way - I simply disagreed with the main point you were making, and still

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-07-01 Thread Stan Hoeppner
design and operation. -- Stan > -Original Message- > From: dovecot-boun...@dovecot.org [mailto:dovecot-boun...@dovecot.org] On > Behalf Of Stan Hoeppner > Sent: Saturday, June 30, 2012 4:24 PM > To: dovecot@dovecot.org > Subject: Re: [Dovecot] RAID1+md concat+XFS as mail

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-30 Thread Костырев Александр Алексеевич
@dovecot.org Subject: Re: [Dovecot] RAID1+md concat+XFS as mailstorage On 6/28/2012 7:15 AM, Ed W wrote: > On 28/06/2012 13:01, Костырев Александр Алексеевич wrote: >> somewhere in maillist I've seen RAID1+md concat+XFS being promoted as >> mailstorage. >> Does anybody in he

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-29 Thread Stan Hoeppner
On 6/28/2012 7:15 AM, Ed W wrote: > On 28/06/2012 13:01, Костырев Александр Алексеевич wrote: >> somewhere in maillist I've seen RAID1+md concat+XFS being promoted as >> mailstorage. >> Does anybody in here actually use this setup? >> >> I've decided to give it a try, >> but ended up with not bein

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-29 Thread Ed W
On 29/06/2012 12:15, Charles Marcus wrote: On 2012-06-28 4:35 PM, Ed W wrote: On 28/06/2012 17:54, Charles Marcus wrote: RAID10 also statistically has a much better chance of surviving a multi drive failure than RAID5 or 6, because it will only die if two drives in the same pair fail, and only

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-29 Thread Charles Marcus
On 2012-06-29 1:02 AM, Dr Josef Karthauser wrote: I will never rely on a non-checksumming file system for production use again, for data that is existed to persist over time. Nice! I'm seriously considering buying a Nexenta Storage device if/when our storage needs require it... this just make

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-29 Thread Dr Josef Karthauser
Kelsey Cummings wrote: > On 06/28/12 05:56, Ed W wrote: >> So given the statistics show us that 2 disk failures are much more >> common than we expect, and that "silent corruption" is likely occurring >> within (larger) real world file stores, there really aren't many battle >> tested options that

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-29 Thread Charles Marcus
On 2012-06-29 2:19 AM, Wojciech Puchar wrote: Has anyone tried or benchmarked ZFS, perhaps ZFS+NFS as backing store for yes. long time ago. ZFS isn't useful for anything more than a toy. I/O performance is just bad. Please stop with the FUD... 'long time ago'? No elaboration on what implem

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-29 Thread Charles Marcus
On 2012-06-28 4:35 PM, Ed W wrote: On 28/06/2012 17:54, Charles Marcus wrote: RAID10 also statistically has a much better chance of surviving a multi drive failure than RAID5 or 6, because it will only die if two drives in the same pair fail, and only then if the second one fails before the hot

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Wojciech Puchar
Has anyone tried or benchmarked ZFS, perhaps ZFS+NFS as backing store for yes. long time ago. ZFS isn't useful for anything more than a toy. I/O performance is just bad.

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Wojciech Puchar
The executive summary is something like: when raid5 fails, because at that point you effectively do a raid "scrub" you tend to suddenly notice a bunch of other hidden problems which were lurking and your rebuild fails (this and no raid will protect you from every failure. You have to do backups

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Kelsey Cummings
On 06/28/12 05:56, Ed W wrote: So given the statistics show us that 2 disk failures are much more common than we expect, and that "silent corruption" is likely occurring within (larger) real world file stores, there really aren't many battle tested options that can protect against this - really

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Ed W
On 28/06/2012 17:54, Charles Marcus wrote: On 2012-06-28 12:20 PM, Ed W wrote: Bad things are going to happen if you loose a complete chunk of your filesystem. I think the current state of the world is that you should assume that realistically you will be looking to your backups if you loose t

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Charles Marcus
On 2012-06-28 12:20 PM, Ed W wrote: Bad things are going to happen if you loose a complete chunk of your filesystem. I think the current state of the world is that you should assume that realistically you will be looking to your backups if you loose the wrong 2 disks in a raid1 or raid10 array.

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Ed W
On 28/06/2012 14:06, Костырев Александр Алексеевич wrote: - RAID1 pairs, plus some kind of intelligent overlay filesystem, eg md-linear+XFS / BTRFS. With the filesystem aware of the underlying arrangement it can theoretically optimise file placement and dramatically increase write speeds for smal

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Костырев Александр Алексеевич
>- RAID1 pairs, plus some kind of intelligent overlay filesystem, eg >md-linear+XFS / BTRFS. With the filesystem aware of the underlying >arrangement it can theoretically optimise file placement and >dramatically increase write speeds for small files in the same manner >that RAID-0 theoreticall

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Ed W
On 28/06/2012 13:46, Wojciech Puchar wrote: (unless we are talking temporary removal and re-insertion?) nope, I'm talking about complete pair's crash when two disks die. I do understand that's the possibility of such outcome (when two disks in the same pair crash) is not high, but when we have

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Wojciech Puchar
(unless we are talking temporary removal and re-insertion?) nope, I'm talking about complete pair's crash when two disks die. I do understand that's the possibility of such outcome (when two disks in the same pair crash) is not high, but when we have 12 or 24 disks in storage... then may 6-12

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Костырев Александр Алексеевич
, 2012 11:15 PM To: dovecot@dovecot.org Subject: Re: [Dovecot] RAID1+md concat+XFS as mailstorage On 28/06/2012 13:01, Костырев Александр Алексеевич wrote: > Hello! > > somewhere in maillist I've seen RAID1+md concat+XFS being promoted as > mailstorage. > Does anybody in here

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Wojciech Puchar
Note that you wouldn't get anything back from a similar fail of a RAID10 array either (unless we are talking temporary removal and re-insertion?) use multiple RAID1 arrays, 2 drives each, one filesystem each.

Re: [Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Ed W
On 28/06/2012 13:01, Костырев Александр Алексеевич wrote: Hello! somewhere in maillist I've seen RAID1+md concat+XFS being promoted as mailstorage. Does anybody in here actually use this setup? I've decided to give it a try, but ended up with not being able to recover any data off survived pai

[Dovecot] RAID1+md concat+XFS as mailstorage

2012-06-28 Thread Костырев Александр Алексеевич
Hello! somewhere in maillist I've seen RAID1+md concat+XFS being promoted as mailstorage. Does anybody in here actually use this setup? I've decided to give it a try, but ended up with not being able to recover any data off survived pairs from linear array when _the_first of raid1 pairs got do