Chris Gerhard wrote: > Is there any way to control the resliver speed? Having attached a third disk > to a mirror (so I can replace the other disks with larger ones) the resilver > goes at a fraction of the speed of the same operation using disk suite. > However it still renders the system pretty much unusable for anything else. >
Resilvers work at low priority in the ZFS scheduler. In general, they work at the media speed of the disk being resilvered. However, anecdotal evidence suggests that this may be impacted by the number and extent of snapshots. I have a lot of characterization data for resilvers, but without varying the scope and number of snapshots (which is a hard thing to identify). ZFS resilvers in time sequence, not by disk block location, so there are many more variables at play here than might be immediately obvious. > So I would like to control the rate of the resilver. Either slow it down a > lot so that the system is still usable or tell it to go as fast as possible > to get it overwith. > There are two competing RFEs for this: http://bugs.opensolaris.org/view_bug.do?bug_id=6592835 http://bugs.opensolaris.org/view_bug.do?bug_id=6494473 > Also does the resilver deliberately pause? Running iostat I see that it will > pause for five to ten seconds where no IO is done at all, then it continues > on at a more reasonable pace. > I have not seen such behaviour during resilver characterization. Which OS release are you using? Also, are you using IDE disks or disks which do not handle multiple outstanding operations? You may also be seeing http://bugs.opensolaris.org/view_bug.do?bug_id=6729696 -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
