Date: Fri, 13 Jul 2012 08:25:36 -0700 From: Dennis Glatting <freebsd@pki2.com> To: freebsd-fs@freebsd.org Subject: Re: ZFS hanging Message-ID: <1342193136.60708.16.camel@btw.pki2.com> In-Reply-To: <20120713170632.065e650e@fabiankeil.de> References: <1341864787.32803.43.camel@btw.pki2.com> <20120712151541.7f3a6886@fabiankeil.de> <CAEJYa-RFuJKTOd3_Ykj3Z8KYPuYoQUwiwOr5i37C0FeZ2MUsvw@mail.gmail.com> <20120713170632.065e650e@fabiankeil.de>
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On Fri, 2012-07-13 at 17:06 +0200, Fabian Keil wrote: > Lytochkin Boris <lytboris@gmail.com> wrote: > > > On Thu, Jul 12, 2012 at 5:15 PM, Fabian Keil > > <freebsd-listen@fabiankeil.de> wrote: > > > fk@r500 ~ $zpool status > > > load: 0.15 cmd: zpool 2698 [spa_namespace_lock] 543.23r 0.00u 0.12s 0% 2908k > > > > This sounds familiar with http://www.freebsd.org/cgi/query-pr.cgi?pr=163770 > > Try playing with kern.maxvnodes. > > Thanks for the suggestion, but the system is my laptop and I already > set kern.maxvnodes=400000 which I suspect is more than I'll ever need. > > Currently I uses less than a tenth of this, but I'll keep an eye on > it the next time the issue occurs. > > I usually reach this deadlock after losing the vdev in a single-vdev pool. > My suspicion is that the deadlock is caused by some kind of "failure to > communicate" between ZFS and the various geom layers involved. > > I already know that losing vdevs with the pool configuration I use > can cause http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/162010 > and http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/162036 and I > suspect that the deadlock is just another symptom of the same issue. > What is the math and constraints behind kern.maxvnodes and how would a reasonable value be chosen? On some of my systems (default): iirc# sysctl -a | grep kern.maxvnodes kern.maxvnodes: 1097048 bd3# sysctl -a | grep kern.maxvnodes kern.maxvnodes: 587825 mc# sysctl -a | grep kern.maxvnodes kern.maxvnodes: 2112911 btw# sysctl -a | grep kern.maxvnodes kern.maxvnodes: 460985 > Fabian
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