On Tue, Dec 29, 2009 at 18:16, Brad <bene...@yahoo.com> wrote: > @eric > > "As a general rule of thumb, each vdev has the random performance > roughly the same as a single member of that vdev. Having six RAIDZ > vdevs in a pool should give roughly the performance as a stripe of six > bare drives, for random IO." > > It sounds like we'll need 16 vdevs striped in a pool to at least get the > performance of 15 drives plus another 16 mirrored for redundancy. > > If we are bounded in iops by the vdev, would it make sense to go with the > bare minimum of drives (3) per vdev?
Minimum is 1 drive per vdev. Minimum with redundancy is 2 if you use mirroring. You should do mirroring to get the best performance. > "This winds up looking similar to RAID10 in layout, in that you're > striping across a lot of disks that each consists of a mirror, though > the checksumming rules are different. Performance should also be > similar, though it's possible RAID10 may give slightly better random > read performance at the expense of some data quality guarantees, since > I don't believe RAID10 normally validates checksums on returned data > if the device didn't return an error. In normal practice, RAID10 and > a pool of mirrored vdevs should benchmark against each other within > your margin of error." > > That's interesting to know that with ZFS's implementation of raid10 it > doesn't have checksumming built-in. He was talking about RAID10, not mirroring in ZFS. ZFS will always use checksums. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
