Date: Mon, 12 Apr 2010 13:11:37 +0400 From: "Alexandr D. Sergeev" <ales@ripn.net> To: freebsd-performance@freebsd.org Subject: Re: Extreme performance falling on ZFS by durable operation of a server Message-ID: <20100412091136.GE61157@runo.ripn.net> In-Reply-To: <20100409024409.GA1602@runo.ripn.net> References: <20100408153257.GA35557@runo.ripn.net> <y2k82c4140e1004081314s7a44ed0g1b833dc1e8a011a7@mail.gmail.com> <20100409024409.GA1602@runo.ripn.net>
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Whether there are any ideas about the reasons of such problems? Whether transition to FreeBSD 8.0 RELEASE / STABLE can help? ZFS in it is declared as "bug free" On Fri, Apr 09, 2010 at 06:44:09AM +0400, Alexandr D. Sergeev wrote: > On Thu, Apr 08, 2010 at 01:14:42PM -0700, K. Macy wrote: > > Hi Alexandr, > > Hi Kip, > > > > > - How much memory do you have? > > 4Gb. > Applications consume a lot of memory, is partially used swap (~1Gb, but without active i/o). > > We have planned increase in memory to 16G > > > > > - What are your ARC settings? > > Settings is default, that recommended for amd64 kernel. > But I am not assured that it is optimal. > Thus sysctl variables are automatically sets to: > vfs.zfs.arc_max ~800Mb > vfs.zfs.arc_mim ~128Mb > > Now the next reboot was required. > Together with which following settings have been made: > > vm.kmem_size=2048M > vfs.zfs.arc_max=1536M > vfs.zfs.arc_min=1024M > vfs.zfs.vdev.cache.size=64M > > Let's look, as it will affect. > > However there is confidence that no problem at a size of ARC. > Even at 200Mb ARC, productivity should not fall so strongly. > > > > > Thanks, > > Kip > > > > On Thu, Apr 8, 2010 at 8:32 AM, Alexandr D. Sergeev <ales@ripn.net> wrote: > > > Hi, all! > > > > > > There are problems with a server on FreeBSD 7.2 CURRENT (6 Jul 2009), carrying out the task of mail server SMTP, IMAP. > > > > > > Messages are stored in maildirs on file system ZFS (mirror of 2 SAS 3k drives). > > > Dovecot is used as IMAP server. > > > > > > After reboot the system works perfectly, however, somewhere in a month, at the same load, arise periodic long delays at opening of new letters. > > > > > > Judging by output iostat -x -w 1, during these moments the disk subsystem is strongly loaded. > > > %busy disks comes nearer to 100 %. Readings nearby 300 per sec prevail. and approx. 10MBytes per sec. > > > > > > Somebody can advise, what diagnostics needed, for understanding of the reason of problems? > > > > > > There is an opinion that a problem with ZFS. > > > > > > Probably, it does not have enough memory. Because during the periods of occurrence of a problem, ARC is have less 300MB: > > > > > > vmstat -m > > > ... > > > solaris 1245732 274745K - 25872717949 16,32,64,128,256,512,1024,2048,4096 > > > ... > > > > > > Or it is bug of ZFS implementation. > > > > > > -- > > > Best regards, > > > Alexandr D.Sergeev > > > _______________________________________________ > > > freebsd-performance@freebsd.org mailing list > > > http://lists.freebsd.org/mailman/listinfo/freebsd-performance > > > To unsubscribe, send any mail to "freebsd-performance-unsubscribe@freebsd.org" > > > > -- Best regards, Alexandr D.Sergeev
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