Jeff Cheeney
2007-Nov-19 22:53 UTC
[zfs-discuss] [storage-discuss] OpenSolaris Wish List - Questions about ZFS prioritized resilvering
Hey ZFS crew ... do you want to jump in and help answer these questions? On 11/19/07 04:13, Ross wrote:> Heya, > > This is a question based on a feature request I saw in the wiki: > http://www.genunix.org/wiki/index.php/OpenSolaris_Storage_Developer_Wish_List > > I''m a complete newbie to all this so didn''t want to clutter the wiki with questions, instead I''ve just added a quick link to here. Hope that''s ok. > > I''ve love to see prioritised resilvering, but I''ve read that snapshots can''t be taken while resilvering is in progress, or that taking a snapshot restarts the resilvering? (is this bug still current? http://bugs.opensolaris.org/view_bug.do?bug_id=6343667). > > Are there plans to address that as part of this? We''re planning to use automated snapshots on a thumper used as a SAN, so we don''t want resilvering to affect the users, but we definately want snapshots to continue while the resilver operation is taking place. That''s expecially important since resilvering a 500MB drive could take some time, and our long term plans involve using resilvering to upgrade to 2TB or even 4TB disks. > > Also, would it be possible to set multiple priority levels for this? We''re planning to use dual parity raid, so if one disk fails I''ve no problem with re-silvering at a steady rate with minimal impact on performance. However, if two disks failed I would want the resilvering to proceed at a much more aggressive pace. > > Would a sensible default be to have resilvering running at a lower priority than other requests while the zpool is still in a redundant configuration, but for the priority to automatically be placed higher than other requests if data is at risk? > > And is there any way administrators would be able to set those rates on the fly, in a relatively easy to understand fashion? If the zpool data was still safe, I''d want to set the resilvering priority so we''d only loose 1/5 of our maximum performance. If data were at risk though, I may want to set that as high as 3/5 or 4/5. How hard would it be to let us configure this using percentages of maximum performance instead of just setting priority levels? > > Also, since we''re planning to use this to upgradea the thumper, and since that means swopping out 48 disks, I''d want to be able to change the resilver priority for a zpool on the fly. That would let us inform the users to expect slower speeds for a while and increase the priority while the upgrade takes place. > > And finally, could priorities be set on a zvol or filesystem basis? We''ll be building one huge pool on the thumper, but some systems will be more imporant than others. If I could assign a global zpool priority, but tweak that for each volume or filesystem, that would be superb. > > > This message posted from opensolaris.org > _______________________________________________ > storage-discuss mailing list > storage-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/storage-discuss >