On Thu, May 6, 2010 at 1:18 AM, Edward Ned Harvey <solar...@nedharvey.com>wrote:
> > From the information I've been reading about the loss of a ZIL device, > What the heck? Didn't I just answer that question? > I know I said this is answered in ZFS Best Practices Guide. > > http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide#Sepa > rate_Log_Devices > > Prior to pool version 19, if you have an unmirrored log device that fails, > your whole pool is permanently lost. > Prior to pool version 19, mirroring the log device is highly recommended. > In pool version 19 or greater, if an unmirrored log device fails during > operation, the system reverts to the default behavior, using blocks from > the > main storage pool for the ZIL, just as if the log device had been > gracefully > removed via the "zpool remove" command. > This week I've had a bad experience replacing a SSD device that was in a hardware RAID-1 volume. While rebuilding, the source SSD failed and the volume was brought off-line by the controller. The server kept working just fine but seemed to have switched from the 30-second interval to all writes going directly to the disks. I could confirm this with iostat. We've had some compatibility issues between LSI MegaRAID cards and a few MTRON SSDs and I didn't believe the SSD had really died. So I brought it off-line and back on-line and everything started to work. ZFS showed the log device c3t1d0 as removed. After the RAID-1 volume was back I replaced that device with itself and a resilver process started. I don't know what it was resilvering against but it took 2h10min. I should have probably tried a zpool offline/online too. So I think if a log device fails AND you've to import your pool later (server rebooted, etc)... then you lost your pool (prior to version 19). Right ? This happened on OpenSolaris 2009.6. -- Giovanni
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