On Mon, 9 Mar 2009, Lars-Gunnar Persson wrote:
1. On the external disk array, I not able to configure JBOD or RAID 0 or 1 with just one disk. I can't find any options for my Solaris server to access the disk directly so I have to configure some raids on the SATABeast. I was thinking of striping two disks in each raid and then add all 7 raids to one zpool as a zraid. The problem with this is if one disk breaks down, I'll loose one RAID 0 disk but maybe ZFS can handle this? Should I rather implement RAID5 disks one the SATABeast and then export them to the Solaris machine? 14 disks would give me 4 RAID5 volumes and 2 spare disks? I'll loose a lot of disk space. What about create larger RAID volumes on the SATABeast? Like 3 RAID volumes with 5 disks in 2 RAIDS and 4 disks in one RAID? I'm really not sure what to choose ... At the moment I've striped two disks in one RAID volume.
Your idea to stripe two disks per LUN should work. Make sure to use raidz2 rather than plain raidz for the extra reliability. This solution is optimized for high data throughput from one user.
An alternative is to create individual "RAID 0" LUNs which actually only contain a single disk. Then implement the pool as two raidz2s with six LUNs each, and two hot spares. That would be my own preference. Due to ZFS's load share this should provide better performance (perhaps 2X) for multi-user loads. Some testing may be required to make sure that your hardware is happy with this.
Avoid RAID5 if you can because it is not as reliable with today's large disks and the resulting huge LUN size can take a long time to resilver if the RAID5 should fail (or be considered to have failed). There is also the issue that a RAID array bug might cause transient wrong data to be returned and this could cause confusion for ZFS's own diagnostics/repair and result in useless "repairs". If ZFS reports a problem but the RAID array says that the data is fine, then there is confusion, finger-pointing, and likely a post to this list. If you are already using ZFS, then you might as well use ZFS for most of the error detection/correction as well.
These are my own opinions and others will surely differ. Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, 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
