> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > boun...@opensolaris.org] On Behalf Of v > > for zfs raidz1, I know for random io, iops of a raidz1 vdev eqaul to > one physical disk iops, since raidz1 is like raid5 , so is raid5 has > same performance like raidz1? ie. random iops equal to one physical > disk's ipos.
I tested this extensively about 6 months ago. Please see http://www.nedharvey.com for more details. I disagree with the assumptions you've made above, and I'll say this instead: Look at http://nedharvey.com/iozone_weezer/bobs%20method/iozone%20results%20summary. pdf Go down to the 2nd section, "Compared to a single disk" Look at "single-disk" and "raidz-5disks" and "raid5-5disks-hardware" You'll see that both raidz and raid5 are significantly faster than a single disk in all types of operations. In all cases, raidz is approximately equal to, or significantly faster than hardware raid5. Furthermore, I later went on to test performance using nonvolatile devices (such as SSD) for ZIL dedicated log device, and in those situations, the performance of ZFS with dedicated log device beat hardware writeback caching easily. So put simply: ZFS raid is faster than the fastest hardware raid. Because ZFS has knowledge of the filesystem and blocks, while hardware raid only has knowledge of the blocks. So ZFS is able to be more intelligent in the techniques it uses for acceleration. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
