Hi, the corners I am basing my previous idea on you can find here: http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide#RAIDZ_Configuration_Requirements_and_Recommendations I can confirm some of the recommendations already from personal practise. First and foremost this sentence: "The recommended number of disks per group is between 3 and 9. If you have more disks, use multiple groups." One example: I am running 11+1 disks in a single group now. I have recently changed the configuration from raidz to raidz2, and the performance while scrub dropped from 500 MB/s to app. 200 MB/s by the imposition of the second parity. I am sure that if I had chosen two groups in raidz, the performance would have been even better than the original config while I could still loose two drives in the pool unless the loss wouldn't occur within a single group. The bottom line is that while increasing the number of stripes in a group the performance, especially random I/O, will converge against the performance of a single group member. The only reason why I am sticking with the single group configuration myself is that performance is "good enough" for what I am doing for now, and that "11 is not so far from 9".
In your case, there are two other aspects: - if you pool small devices as JBODS below a vdev member, no parity will help you when you loose a member of the underlying JBOD. - If you use slices as vdev members, performance will drop dramatically. Regards, tonmaus -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
