Date: Fri, 09 Apr 2010 06:44:09 +0400 From: "Alexandr D. Sergeev" <ales@ripn.net> To: "K. Macy" <kmacy@freebsd.org> Cc: freebsd-performance@freebsd.org Subject: Re: Extreme performance falling on ZFS by durable operation of a server Message-ID: <20100409024409.GA1602@runo.ripn.net> In-Reply-To: <y2k82c4140e1004081314s7a44ed0g1b833dc1e8a011a7@mail.gmail.com> References: <20100408153257.GA35557@runo.ripn.net> <y2k82c4140e1004081314s7a44ed0g1b833dc1e8a011a7@mail.gmail.com>
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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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