Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-25 Thread Ed Plese
On Tue, Oct 24, 2006 at 03:31:41PM -0400, Dale Ghent wrote: > Okay, then if the person can stand to lose even more space, do zfs > mirroring on each JBOD. Then we'd have a mirror of mirrors instead of > a mirror of raidz's. > > Remember, the OP wanted chassis-level redundancy as well as > re

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-25 Thread Jeremy Teo
On 10/25/06, Jonathan Edwards <[EMAIL PROTECTED]> wrote: On Oct 24, 2006, at 12:26, Dale Ghent wrote: > On Oct 24, 2006, at 12:33 PM, Frank Cusack wrote: > >> On October 24, 2006 9:19:07 AM -0700 "Anton B. Rang" >> <[EMAIL PROTECTED]> wrote: Our thinking is that if you want more redundancy

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Torrey McMahon
Frank Cusack wrote: I don't think we know what the OP wanted. :-) I understand the paranoia around overlapping raid levels - And yes they are out to get you - but in the past some of the requirements were around performance in a failure mode. Do we have any data concerning the performance

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Frank Cusack
On October 24, 2006 3:31:41 PM -0400 Dale Ghent <[EMAIL PROTECTED]> wrote: On Oct 24, 2006, at 3:23 PM, Frank Cusack wrote: says a raid-z vdev has the read throughput of 1 drive for random reads. Compared to #drives for a stripe. That's pre

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Dale Ghent
On Oct 24, 2006, at 3:23 PM, Frank Cusack wrote: says a raid-z vdev has the read throughput of 1 drive for random reads. Compared to #drives for a stripe. That's pretty significant. Okay, then if the person can stand to lose even more spac

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Frank Cusack
On October 24, 2006 3:15:10 PM -0400 Dale Ghent <[EMAIL PROTECTED]> wrote: On Oct 24, 2006, at 2:46 PM, Richard Elling - PAE wrote: Pedantic question, what would this gain us other than better data retention? Space and (especially?) performance would be worse with RAID-Z+1 than 2-way mirrors.

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Jonathan Edwards
there's 2 approaches: 1) RAID 1+Z where you mirror the individual drives across trays and then RAID-Z the whole thing 2) RAID Z+1 where you RAIDZ each tray and then mirror them I would argue that you can lose the most drives in configuration 1 and stay alive: With a simple mirrored stripe

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Dale Ghent
On Oct 24, 2006, at 2:46 PM, Richard Elling - PAE wrote: Pedantic question, what would this gain us other than better data retention? Space and (especially?) performance would be worse with RAID-Z+1 than 2-way mirrors. You answered your own question, it would gain the user better data retent

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Richard Elling - PAE
Pedantic question, what would this gain us other than better data retention? Space and (especially?) performance would be worse with RAID-Z+1 than 2-way mirrors. -- richard Frank Cusack wrote: On October 24, 2006 9:19:07 AM -0700 "Anton B. Rang" <[EMAIL PROTECTED]> wrote: Our thinking is that

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Jonathan Edwards
On Oct 24, 2006, at 12:26, Dale Ghent wrote: On Oct 24, 2006, at 12:33 PM, Frank Cusack wrote: On October 24, 2006 9:19:07 AM -0700 "Anton B. Rang" <[EMAIL PROTECTED]> wrote: Our thinking is that if you want more redundancy than RAID-Z, you should use RAID-Z with double parity, which provi

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Frank Cusack
On October 24, 2006 2:26:49 PM -0400 Dale Ghent <[EMAIL PROTECTED]> wrote: Since the person is dealing with JBODS and not hardware RAID arrays, my suggestion is to combine ZFS and SVM. 1) Use ZFS and make a raidz-based ZVOL of disks on each of the two JBODs 2) Use SVM to mirror the two ZVOLs. N

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Dale Ghent
On Oct 24, 2006, at 12:33 PM, Frank Cusack wrote: On October 24, 2006 9:19:07 AM -0700 "Anton B. Rang" <[EMAIL PROTECTED]> wrote: Our thinking is that if you want more redundancy than RAID-Z, you should use RAID-Z with double parity, which provides more reliability and more usable storage

Re: [zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Frank Cusack
On October 24, 2006 9:19:07 AM -0700 "Anton B. Rang" <[EMAIL PROTECTED]> wrote: Our thinking is that if you want more redundancy than RAID-Z, you should use RAID-Z with double parity, which provides more reliability and more usable storage than a mirror of RAID-Zs would. This is only true if th

[zfs-discuss] Re: Mirrored Raidz

2006-10-24 Thread Anton B. Rang
>Our thinking is that if you want more redundancy than RAID-Z, you should >use RAID-Z with double parity, which provides more reliability and more >usable storage than a mirror of RAID-Zs would. This is only true if the drives have either independent or identical failure modes, I think. Consid

[zfs-discuss] Re: Mirrored Raidz

2006-10-20 Thread Jeb Campbell
Don't know if you are running current OpenSolaris or can wait for Solaris 10 11/06 (should be released in November). Either of those will contain raidz2 (which is like raid6 where you lose 2 disks). For max space with some redundancy, I would make one raidz2 vdev of all 8 disks. You will get