> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > boun...@opensolaris.org] On Behalf Of Edward Ned Harvey > > The characteristic that *really* makes a big difference is the number > of > slabs in the pool. i.e. if your filesystem is composed of mostly small > files or fragments, versus mostly large unfragmented files.
Oh, if at least some of my reasoning was correct, there is one valuable take-away point for hatish: Given some number X total slabs used in the whole pool. If you use a single vdev for the whole pool, you will have X partial slabs written on each disk. If you have 2 vdev's, you'll have approx X/2 partial slabs written on each disk. 3 vdevs ~> X/3 partial slabs on each disk. Therefore, the resilver time approximately divides by the number of separate vdev's you are using in your pool. So the largest factor affecting resilver time of a single large vdev versus many smaller vdev's is NOT the quantity of data written on each disk, but just the fact that fewer slabs are used on each disk when using smaller vdev's. If you want to choose between (a) 21disk raidz3 versus (b) 3 vdevs of each 7disk raidz1, then: The raidz3 provides better redundancy, but has the disadvantage that every slab must be partially written on every disk. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
