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's between myself (the new guy that embraces new technologies) vs a EMC "lover" sysadmin... Currently the system is configured with 4 vdevs each with 5 drives, and i'm considering to use the 4 others ones to create something a raid10 (usefull for the backup software indexes...) . So far the system seems to behave quite nice...but than again we are just starting it. Thanks for the input, Bruno On 25-3-2010 16:46, Freddie Cash wrote: > On Thu, Mar 25, 2010 at 6:28 AM, Bruno Sousa <bso...@epinfante.com > <mailto: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 <mailto:fjwc...@gmail.com> > > -- > This message has been scanned for viruses and > dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is > believed to be clean. > > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >
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