Re: ZFS memory management

>
>  - 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

And this is what Nikolay did after the incident apparently. The question
was more like:
Shouldn't the OS release this memory automatically when it's starved as
opposed to
nuking processes? It's only cache after all. Lots of it.

On Tue, Nov 27, 2012 at 12:22 PM, Freddie Cash <fjwcash@gmail.com> wrote:

> 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
>
> :)
>
>
> On Tue, Nov 27, 2012 at 12:10 PM, Nikolay Denev <ndenev@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
> > /etc/sysctl.conf.
> > 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.
> >
> > Cheers,
> > Nikolay
> >
> >
> > _______________________________________________
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> "
> >
>
>
>
> --
> Freddie Cash
> fjwcash@gmail.com
> _______________________________________________
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>

-- 
Rumen Telbizov
http://telbizov.com
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