Re: [zfs-discuss] RAIDZ2 configuration

2010-04-01 Thread Carson Gaspar
Brandon High wrote: On Thu, Apr 1, 2010 at 11:46 AM, Carson Gaspar > wrote: "Nonsensical" may be a bit strong, but I can see no possible use case where a 3 disk raidz2 isn't better served by a 3-way mirror. Once bp_rewrite is done, you'll be able add disks to

Re: [zfs-discuss] RAIDZ2 configuration

2010-04-01 Thread Brandon High
On Thu, Apr 1, 2010 at 11:46 AM, Carson Gaspar wrote: > "Nonsensical" may be a bit strong, but I can see no possible use case where > a 3 disk raidz2 isn't better served by a 3-way mirror. > Once bp_rewrite is done, you'll be able add disks to the raidz2. I suppose that's one reason? -B -- Br

Re: [zfs-discuss] RAIDZ2 configuration

2010-04-01 Thread Carson Gaspar
Cindy Swearingen wrote: If someone new to ZFS wants to take 3 old (but reliable) disks and make a raidz2 configuration for testing, we would not consider this is a nonsensical idea. You can then apply what you learn about ZFS space allocation and redundancy to a new configuration. "Nonsensical

Re: [zfs-discuss] RAIDZ2 configuration

2010-04-01 Thread Cindy Swearingen
Behalf Of *Bruno Sousa *Sent:* Thursday, March 25, 2010 3:28 PM *To:* Freddie Cash *Cc:* ZFS filesystem discussion list *Subject:* Re: [zfs-discuss] RAIDZ2 configuration Hmm...it might be completely wrong , but the idea of raidz2 vdev with 3 disks came from the reading of http://docs.sun.co

Re: [zfs-discuss] RAIDZ2 configuration

2010-04-01 Thread Cindy Swearingen
filesystem discussion list *Subject:* Re: [zfs-discuss] RAIDZ2 configuration Hmm...it might be completely wrong , but the idea of raidz2 vdev with 3 disks came from the reading of http://docs.sun.com/app/docs/doc/819-5461/gcvjg?a=view . This particular page has the following example : *zpool c

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-31 Thread Bruno Sousa
, for doing this to your poor unfortunate >> readers. It would be nice if the page were a wiki, or somehow able >> to have feedback submitted… >> >> >> >> >> >> >> >> *From:* zfs-discuss-boun...@opensolaris.org >> [mailto:zfs-discuss-boun...@opensolaris.

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-31 Thread Cindy Swearingen
...@opensolaris.org [mailto:zfs-discuss-boun...@opensolaris.org] *On Behalf Of *Bruno Sousa *Sent:* Thursday, March 25, 2010 3:28 PM *To:* Freddie Cash *Cc:* ZFS filesystem discussion list *Subject:* Re: [zfs-discuss] RAIDZ2 configuration Hmm...it might be completely wrong , but the idea of raidz2 vdev with 3

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-26 Thread David Magda
On Fri, March 26, 2010 07:38, Edward Ned Harvey wrote: >> Coolio. Learn something new everyday. One more way that raidz is >> different from RAID5/6/etc. > > Freddie, again, you're wrong. Yes, it's perfectly acceptable to create > either raid-5 or raidz using 2 disks. It's not degraded, but it

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-26 Thread Eric D. Mudama
On Fri, Mar 26 at 7:29, Edward Ned Harvey wrote: > Using fewer than 4 disks in a raidz2 defeats the purpose of raidz2, as > you will always be in a degraded mode. Freddie, are you nuts? This is false. Sure you can use raidz2 with 3 disks in it. But it does seem pointless to do th

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-26 Thread Edward Ned Harvey
Behalf Of Bruno Sousa Sent: Thursday, March 25, 2010 3:28 PM To: Freddie Cash Cc: ZFS filesystem discussion list Subject: Re: [zfs-discuss] RAIDZ2 configuration Hmm...it might be completely wrong , but the idea of raidz2 vdev with 3 disks came from the reading of http://docs.sun.com/app/docs/doc

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-26 Thread Edward Ned Harvey
> Coolio. Learn something new everyday. One more way that raidz is > different from RAID5/6/etc. Freddie, again, you're wrong. Yes, it's perfectly acceptable to create either raid-5 or raidz using 2 disks. It's not degraded, but it does seem pointless to do this instead of a mirror. Likewis

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-26 Thread Edward Ned Harvey
> Using fewer than 4 disks in a raidz2 defeats the purpose of raidz2, as > you will always be in a degraded mode. Freddie, are you nuts? This is false. Sure you can use raidz2 with 3 disks in it. But it does seem pointless to do that instead of a 3-way mirror. _

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Carson Gaspar
Freddie Cash wrote: So, is it just a "standard" that hardware/software RAID setups require 3 drives for a RAID5 array? And 4 drives for RAID6? It's padding on the sharp edges. See my earlier post - a 2 disk RAID5 is silly, use a mirror. A 3 disk RAID6 is silly, use a 3-way mirror. Both are

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Freddie Cash
On Thu, Mar 25, 2010 at 12:44 PM, Richard Elling wrote: > On Mar 25, 2010, at 12:10 PM, Freddie Cash wrote: > > > On Thu, Mar 25, 2010 at 11:47 AM, Bruno Sousa > wrote: > > What do you mean by "Using fewer than 4 disks in a raidz2 defeats the > purpose of raidz2, as you will always be in a degrad

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Richard Elling
On Mar 25, 2010, at 12:10 PM, Freddie Cash wrote: > On Thu, Mar 25, 2010 at 11:47 AM, Bruno Sousa wrote: > What do you mean by "Using fewer than 4 disks in a raidz2 defeats the purpose > of raidz2, as you will always be in a degraded mode" ? Does it means that > having 2 vdevs with 3 disks it w

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Victor Latushkin
On Mar 25, 2010, at 22:10, Freddie Cash wrote: On Thu, Mar 25, 2010 at 11:47 AM, Bruno Sousa wrote: What do you mean by "Using fewer than 4 disks in a raidz2 defeats the purpose of raidz2, as you will always be in a degraded mode" ? Does it means that having 2 vdevs with 3 disks it won't

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Bruno Sousa
Hmm...it might be completely wrong , but the idea of raidz2 vdev with 3 disks came from the reading of http://docs.sun.com/app/docs/doc/819-5461/gcvjg?a=view . This particular page has the following example : *zpool create tank raidz2 c1t0d0 c2t0d0 c3t0d0* # *zpool status -v tank* pool: tank s

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Freddie Cash
On Thu, Mar 25, 2010 at 11:47 AM, Bruno Sousa wrote: > What do you mean by "Using fewer than 4 disks in a raidz2 defeats the > purpose of raidz2, as you will always be in a degraded mode" ? Does it means > that having 2 vdevs with 3 disks it won't be redundant in the advent of a > drive failure?

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Richard Jahnel
Well the thing I like about raidz3 is that even with 1 drive out you have 3 copies of all the blocks. So if you encounter bit rot, not only can checksums be used to find the good data, you can still get a best 2 out of 3 vote on which data is correct. As to performance, all I can say is test te

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Carson Gaspar
Bruno Sousa wrote: What do you mean by "Using fewer than 4 disks in a raidz2 defeats the purpose of raidz2, as you will always be in a degraded mode" ? Does it means that having 2 vdevs with 3 disks it won't be redundant in the advent of a drive failure? Technically a 3 disk raidz2 won't be de

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Bruno Sousa
On 25-3-2010 15:28, Richard Jahnel wrote: > I think I would do 3xraidz3 with 8 disks and 0 hotspares. > > That way you have a better chance of resolving bit rot issues that might > become apparent during a rebuild. > Indeed raidz3...i didn't consider it. In short, a raidz3 could sustain 3 brok

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Bruno Sousa
Hi, What do you mean by "Using fewer than 4 disks in a raidz2 defeats the purpose of raidz2, as you will always be in a degraded mode" ? Does it means that having 2 vdevs with 3 disks it won't be redundant in the advent of a drive failure? Indeed it may be too many spares...the discussion here it

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Freddie Cash
On Thu, Mar 25, 2010 at 6:28 AM, Bruno Sousa wrote: > Assuming a system with 24 disks available , having in mind reliability as > the crucial factor , secondary the usable space and finally performance > would be the last criteria, what would be the preferable configuration ? > > Should it be :

Re: [zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Richard Jahnel
I think I would do 3xraidz3 with 8 disks and 0 hotspares. That way you have a better chance of resolving bit rot issues that might become apparent during a rebuild. -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@op

[zfs-discuss] RAIDZ2 configuration

2010-03-25 Thread Bruno Sousa
Hi all, Yet another question regarding raidz configuration.. Assuming a system with 24 disks available , having in mind reliability as the crucial factor , secondary the usable space and finally performance would be the last criteria, what would be the preferable configuration ? Should it be :