@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? "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. -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
