I was perhaps slightly hasty; RAID-5 is more efficient than a 2-disk mirror for reads, but RAID-10 (striping & mirroring) can match (or slightly exceed) its efficiency for small reads. In both cases, there is a single disk accessed.
With 4 disks, RAID-1+0 can service four independent reads concurrently, while RAID-5 can service up to four independent reads concurrently, but perhaps as few as 1 if all reads are directed to the same spindle. Under heavy loads, all spindles will generally be busy, so performance is similar. This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
