On Fri, 16 May 2008, Kenny wrote: > Sun 2540 FC Disk Array w/12 1TB disk drives
It is interesting that the 2540 is available with large disks now. > My desire is to create 2 5disk RAID 5 sets with one hot spare each. > Then using ZFS to pool the 2 sets into one 8 TB Pool with several > ZFS file systems in the pool. > > Now I have several questions: > > 1) Does this plan seem ok? Another option is to export each entire drive as a LUN and put 10 active drives into one zfs pool as two raidzs, or one raidz2. The other two drives can be retained as spares for the pool. If replacement drives are readily sourced on demand, you could use all 12 drives as two raidz2s. This approach does not allow other systems to use the 2540 since one host owns the pool. However, you could move the ZFS pool to another system if need be. > 2) Does anyone have experiance with the 2540? Yes. Please see my white paper at http://www.simplesystems.org/users/bfriesen/zfs-discuss/2540-zfs-performance.pdf which discusses my experience with ZFS and the 2540. The paper was written back in February and I have yet to experience a hickup with the 2540 or ZFS. Not even one bad block. > 3) I've read that it's best practice to create the RAID set > utilizing Hardware RAID utilities vice using ZFS raidz. Any wisdom > on this? This is really a philosophical or requirements issue. The 2540 allows you create pools and then export only part of the pool as a LUN to be used by an initator. This allows you create LUNs on disks which are shared by multiple hosts (initiators), each of which has its own ZFS pool (or traditional filesystem). If you really need to divide up storage at this level, then the 2540 offers flexibility that you won't get from ZFS. A drawback to sharing sliced pools in this way is that if there is a problem with the underlying disks, then multiple hosts may be impacted during recovery. The 2540 CAM provides a 4-disk RAID5 config which claims to be tuned for ZFS. Someone on the list created three 4-disk RAID5 LUNs this way and put them all in one ZFS pool, obtaining very good performance. If one of those LUNs was to irreparably fail, his entire pool would be toast. ZFS experts will tell you that you should not be trusting the 2540 or its firmware to catch all errors and so there should always be redundancy (e.g. mirroring) at the ZFS level. By exporting each 2540 disk as a LUN, then any of the redundancy schemes supported by ZFS (mirror, raidz, raidz2) can be used from the initiator, essentially ignoring the ones built into the 2540. While the 2540's CAM interface is nice, you will find that it is far slower than ZFS is at incorporating your disks (25 tedious minutes in the CAM admin tool vs less than a second for ZFS). Bob ====================================== Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
