2011-06-11 19:15, Pasi Kärkkäinen пишет:
On Sat, Jun 11, 2011 at 08:35:19AM -0500, Edmund White wrote:I've had two incidents where performance tanked suddenly, leaving the VM guests and Nexenta SSH/Web consoles inaccessible and requiring a full reboot of the array to restore functionality. In both cases, it was the Intel X-25M L2ARC SSD that failed or was "offlined". NexentaStor failed to alert me on the cache failure, however the general ZFS FMA alert was visible on the (unresponsive) console screen.The "zpool status" output showed: cache c6t5001517959467B45d0 FAULTED 2 542 0 too many errors This did not trigger any alerts from within Nexenta. I was under the impression that an L2ARC failure would not impact the system. But in this case, it was the culprit. I've never seen any recommendations to RAID L2ARC for resiliency. Removing the bad SSD entirely from the server got me back running, but I'm concerned about the impact of the device failure and the lack of notification from NexentaStor.IIRC recently there was discussion on this list about firmware bug on the Intel X25 SSDs causing them to fail under high disk IO with "reset storms".
Even if so, this does not forgive ZFS hanging - especially if it detected the drive failure, and especially if this drive is not required for redundant operation. I've seen similar bad behaviour on my oi_148a box when I tested USB flash devices as L2ARC caches and occasionally they died by slightly moving out of the USB socket due to vibration or whatever reason ;) Similarly, this oi_148a box hung upon loss of SATA connection to a drive in the raidz2 disk set due to unreliable cable connectors, while it should have stalled IOs to that pool but otherwise the system should have remained remain responsive (tested failmode=continue and failmode=wait on different occasions). So I can relate - these things happen, they do annoy, and I hope they will be fixed sometime soon so that ZFS matches its docs and promises ;) //Jim Klimov _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
