On Thu, Mar 25, 2010 at 6:28 AM, Bruno Sousa <bso...@epinfante.com> 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 : > > - A - 7 raidz2 groups with 3 disks each and 3 disks as hot-spares > - B - 3 raidz2 groups with 7 disks each and 3 disks as hot-spares > - C - 5 raidz2 groups with 4 disks each and 4 disks as hot-spares > - D - 4 raidz2 groups with 5 disks each and 4 disks as hot-spares > - E - other? ;) > > Using fewer than 4 disks in a raidz2 defeats the purpose of raidz2, as you will always be in a degraded mode. Why do you want so many hot-spares? Are you really expecting that many drives to die simultaneously? 1-2 would be plenty for a 24 drive system, if even that many. We have a couple 24-drive storage servers running. They are currently using 3x raidz2 vdevs of 8 drives each, spread across two 12-port controllers (8 on one controller, 8 on the other, 8 spread across the two). If I was to re-do these servers today, I would go with 4x raidz2 vdevs of 6 drives each and either put 2 vdevs on each controller, or switch to using 4 separate 8-port controllers with 1 vdev per controller. We don't use hot-spares, as we have a lot of monitoring to detect when a drive dies or the pool becomes degraded, and have a stack of spare drives standing by to use as replacements. -- Freddie Cash fjwc...@gmail.com
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