ZFS memory management
olivier at gid0.org
Thu Nov 29 14:53:23 UTC 2012
2012/11/27 Freddie Cash <fjwcash at gmail.com>:
> Read any ZFS tuning manual on the web, including the ones direct from
> SUN/Oracle, and they all list:
> - if you are running processes that need a lot of memory, then limit the
> ARC to allow the apps to have access to that memory
Or you could have at least a little swap (good practice) to allow ARC
take the time to evict some memory when under pressure.
> On Tue, Nov 27, 2012 at 12:10 PM, Nikolay Denev <ndenev at gmail.com> wrote:
>> Hello list,
>> I have the following question : I have several machines with 196G of RAM
>> that are using
>> RELENG_9 with ZFS, and are running a very memory intensive java
>> applications - ElasticSearch
>> The machines are without swap configured and have "vm.swap_enabled=0" in
>> The ElasticSearch processes are using mlockall(2) to pin down their memory
>> (configured at 40G).
>> And at this point I thought that there would be no problems, but from time
>> to time, when the machine grows it's
>> ARC memory and there are some other running processes like nginx with
>> passenger and uwsgi the ElasticSearch
>> process would get killed by the kernel OOM killer with reason "no swap
>> space available"
>> Of course, I've now tuned down arc_max in /boot/loader.conf, but isn't
>> this supposed to work automatically? Like
>> ZFS releasing some memory when there is a pressure, instead of the OOM
>> killer going postal? (at the moment when
>> the process was killed the ZFS ARC was 132G).
>> I understand that this might be problematic as AFAIK ZFS releases memory
>> asynchronously when the arc_reclaim_thread() is run,
>> which might take some time to be scheduled and complete.
>> freebsd-stable at freebsd.org mailing list
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> Freddie Cash
> fjwcash at gmail.com
> freebsd-stable at freebsd.org mailing list
> To unsubscribe, send any mail to "freebsd-stable-unsubscribe at freebsd.org"
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