Date: Thu, 21 Jun 2007 12:32:40 +0300 From: Cristian KLEIN <cristi@net.utcluj.ro> To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-fs@freebsd.org, Espen Skoglund <esk@ira.uka.de> Subject: Re: Snapshot usage guidelines (to avoid stability issues) Message-ID: <467A45B8.3070303@net.utcluj.ro> In-Reply-To: <20070621090333.GA2268@deviant.kiev.zoral.com.ua> References: <18041.21810.297355.202403@gargle.gargle.HOWL> <20070620165746.GX2268@deviant.kiev.zoral.com.ua> <4679AE0C.5040306@net.utcluj.ro> <20070621090333.GA2268@deviant.kiev.zoral.com.ua>
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Kostik Belousov wrote: > On Thu, Jun 21, 2007 at 01:45:32AM +0300, Cristian KLEIN wrote: >> Kostik Belousov wrote: >>> On Wed, Jun 20, 2007 at 06:26:26PM +0200, Espen Skoglund wrote: >>>> Hi, >>>> >>>> A couple of days ago I decided to start using snapshots on my system. >>>> Knowing that the functionality has been available for quite some time >>>> now I (apparently wrongly) assumed that it was ready for production >>>> use. My bad. >>>> >>>> My system, a 6-STABLE from week and a half ago, uses two 250GB >>>> gstriped disks and has about 4-5 snapshots on one 215GB UFS partiton. >>>> This morning I learned that things had gone terribly wrong during some >>>> nightly cronjobs, hanging the whole system. Suspecting that snapshots >>>> were the culprit I soon learned after some investigation that the >>>> snapshot functionality wasn't nearly as stable as I had hoped for. >>>> >>>> Looking at PRs and mailing lists there seems to be mainly two >>>> outstanding stability issues with snapshots: a) snapshotted fs running >>>> full, and b) deleting large amount of files on an fs with multiple >>>> snapshots. The former issue, while certainly annoying, one could be >>>> able to work around. The latter issue, on the other hand, seems more >>>> like a definite show stopper. >>>> >>>> Am I right in inferring that the two above cases are main issues with >>>> snaphots at this time, or are there other known gotchas that I have to >>>> look out for. >>> About the issue b). Are you system sources before or after 2007-06-11 >>> 10:53:48 UTC ? Or simply show me the version of sys/ufs/ffs/ffs_snapshot.c. >>> >>> If it is less then 1.103.2.24, see developers handbook for instruction on >>> reporting deadlocks. >>> >> Do you think that 1.103.2.24 might solve this >> http://lists.freebsd.org/pipermail/freebsd-fs/2007-May/003161.html ? > I very much doubt it. AFAIR, I asked at least ddb backtrace for the crash, > and you did not answered. I'm really sorry, but I wasn't able to reproduce the problem on another system. I tried taking / deleting many snapshots while running bonnie++, but the panic would not occur. I have 1,7mil inodes (4% utilization) on the server where the crash occured. Might this be a prerequisite of the panic?
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