Date: Tue, 8 Jan 2013 11:29:30 +0400 (MSK) From: Dmitry Morozovsky <marck@rinet.ru> To: Konstantin Belousov <kostikbel@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: zfs -> ufs rsync: livelock in wdrain state Message-ID: <alpine.BSF.2.00.1301081127340.7949@woozle.rinet.ru> In-Reply-To: <20130108001231.GB82219@kib.kiev.ua> References: <alpine.BSF.2.00.1301080013520.7949@woozle.rinet.ru> <20130108001231.GB82219@kib.kiev.ua>
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On Tue, 8 Jan 2013, Konstantin Belousov wrote: > > Now, during last rsync, the process is stuck as [snip] > > root@moose:/ar# sync > > load: 0.00 cmd: sync 67229 [wdrain] 468.17r 0.00u 0.00s 0% 596k > > > > Any hints? Quick searching throug freebsd mailing lists and/or open PRs does > > not reveal much. > > > > Are there any kernel messages about the disk system ? > > The wdrain means that the amount of the dirty buffers accumulated exceeds > the allowed maximum. The transient 'wdrain' state is normal on a machine > doing lot of writes to a filesystem using buffer cache, say UFS. Failure > to clean the dirty buffers is usually related to the disk i/o stalling. > > It cannot be denied that a bug could cause stuck 'wdrain' state, but > in the last five or so years all the cases I investigated were due to > disks. Yes, it seems so: root@moose:~# camcontrol devlist load: 0.03 cmd: camcontrol 49735 [devfs] 2.68r 0.00u 0.00s 0% 820k and then machine is in well known "hardly alive" state: TCP connects established, process switching does not go. Will investigate the hardware, thank you. -- Sincerely, D.Marck [DM5020, MCK-RIPE, DM3-RIPN] [ FreeBSD committer: marck@FreeBSD.org ] ------------------------------------------------------------------------ *** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru *** ------------------------------------------------------------------------
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