2012-03-21 17:28, Edward Ned Harvey wrote:
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- boun...@opensolaris.org] On Behalf Of MLR
...
Am I correct in thinking this means, for example, I have a single
>> 14 disk raidz2 vdev zpool,
It's not advisable to put more than ~8 disks in a single vdev, because it really hurts during resilver time. Maybe a week or two to resilver like that.
Yes, that's important to note also. While ZFS marketing initially stressed that unlike traditional RAID systems, a "rebuild" of ZFS onto a spare/replacement disk only needs to copy referenced data and not the whole disk, it somehow fell off the picture that such rebuild is a lot of random IO - because the data block tree must be read in as a tree walk, often with emphasis on block "age" (its birth TXG number). If your pool is reasonably full (and who runs it empty?) then this is indeed lots of random IO, and a blind full-disk copy would have gone orders of magnitude faster. The less disk participate in this thrashing - the faster it will go (less data needed overall to reconstruct a disk's worth of sectors from redundancy data). That's the way I understand the problem, anyway... //Jim _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
