Date: Thu, 29 Jan 2015 07:38:50 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 197164] Zpool with L2ARC hangs whole system Message-ID: <bug-197164-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=197164 Bug ID: 197164 Summary: Zpool with L2ARC hangs whole system Product: Base System Version: 10.1-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Many People Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: Karli.Sjoberg@slu.se Created attachment 152328 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=152328&action=edit Graphite - System Overview Hi! At present we have 4 ZFS storage systems that _were_ configured with SSD disks as cache and after different periods of time, depending on amount of RAM and load, they go unresponsive. Initially you can ping them and change VT's at the console but nothing prints when you type, all services are gone etc. After a while they stop responding to ping as well. After a reboot all is good again for a while until the process repeats itself. Now I have found out exactly what´s causing it: L2ARC! Just removing the cache drive(s), they run rock-solid again, but performance is severely degraded. The caching in ZFS really does wonders to offload the "slow" rotating disks and we´d very much like to be able to re-add them to our pools again. This is similar to: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=187594 But this might be another issue. And since the OP couldn´t experiment with the systems being in production, the case couldn´t really come any further, but this one can! We have a virtual machine set up exactly like our "real" storage's, but miniturized in performance and capacity. It´s upgraded to 10.1-RELEASE with these patches applied: https://svnweb.freebsd.org/base?view=revision&revision=272875 With a script that loops copying files from my desktop to the VM and then back again, I have been able to reliably hang the system just by re-adding the cache to the pool, take a look at the attached screenshot. It shows the system overview of this virtual storage server were I was running my script over night and added the cache to the pool at around 9 AM. See what happens with the ARC? That´s the problem. And then it went unresponsive around 3-4 PM. Thanks in advance! Karli Sjöberg -- You are receiving this mail because: You are the assignee for the bug.
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