Date: Thu, 30 Jul 2015 12:49:21 +0100 From: Steven Hartland <killing@multiplay.co.uk> To: freebsd-fs@freebsd.org Subject: Re: ZFS on 10-STABLE r281159: programs, accessing ZFS pauses for minutes in state [*kmem arena] Message-ID: <55BA0F41.6070508@multiplay.co.uk> In-Reply-To: <164833736.20150730143008@serebryakov.spb.ru> References: <164833736.20150730143008@serebryakov.spb.ru>
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On 30/07/2015 12:30, Lev Serebryakov wrote: > Hello Freebsd-fs, > > > I'm migrating my NAS from geom_raid5 + UFS to ZFS raidz. My main storage > is 5x2Tb HDDs. Additionaly, I have 2x3Tb HDDs attached to hold my data when > I re-make my main storage. > > So, I have now two ZFS pools: > > ztemp mirror ada0 ada1 [both are 3Tb HDDS] > zstor raidz ada3 ada4 ada5 ada6 ada7 [all of them are 2Tb] > > ztemp contain one filesystem with 2.1Tb of my data. ztemp was populated > with my data from old geom_raid5 + UFS installation via "rsync" and it was > FAST (HDD-speed). > > zstor contains several empty file systems (one per user), like: > > zstor/home/lev > zstor/home/sveta > zstor/home/nsvn > zstor/home/torrents > zstor/home/storage > > Deduplication IS TURNED OFF. atime is turned off. Record size set to 1M as > I have a lot of big files (movies, RAW photo from DSLR, etc). Compression is > turned off. You don't need to do that as record set size is a min not a max, if you don't force it large files will still be stored efficiently. > When I try to copy all my data from temporary HDDs (ztemp pool) to my new > shiny RIAD (zstor pool) with > > cd /ztemp/fs && rsync -avH lev sveta nsvn storage /usr/home/ > > rsync pauses for tens of minutes (!) after several hundreds of files. ^T > and top shows state "[*kmem arena]". When I stop rsync with ^C and try to do > "zfs list" it waits forever, in state "[*kmem arena]" again. > > This server is equipped with 6GiB of RAM. > > It looks FreeBSD contains bug about year ago which leads to this behavior, > but mailing lists says, that it was fixed in r272221, 10 months ago. When this happens what is the state of memory on the machine? Top will give a good overview, while sysctl vm.stats.vm and vmstat -z will provide some detail. If you're seeing significant memory pressure, which could well be the case with a mixed ZFS UFS system during this transfer (they use competing memory resource pools) then you could try limiting ARC via vfs.zfs.arc_max You could also see if the patch on https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=187594 help. Regards Steve
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