Extreme performance falling on ZFS by durable operation of a server

[K. Macy]

8-STABLE is definitely better, but you should also set arc_min to at
least 384M-512M. I'm not sure that arc_min is even honored under 7.2.

-Kip


On Mon, Apr 12, 2010 at 2:11 AM, Alexandr D. Sergeev <ales at ripn.net> wrote:
> 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 at 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 at freebsd.org mailing list
>> > > http://lists.freebsd.org/mailman/listinfo/freebsd-performance
>> > > To unsubscribe, send any mail to "freebsd-performance-unsubscribe at freebsd.org"
>> > >
>>
>
> --
> Best regards,
> Alexandr D.Sergeev
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