Re: free RAM not being used for page cache

On Wed, Jul 30, 2014 at 12:57 PM, Kevin Goess <kgoess(at)bepress(dot)com> wrote:
> On Wed, Jul 30, 2014 at 11:49 AM, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
>> On Wed, Jul 30, 2014 at 12:51 PM, Kevin Goess <kgoess(at)bepress(dot)com> wrote:
>> > A couple months ago we upgraded the RAM on our database servers from
>> > 48GB to
>> > 64GB. Immediately afterwards the new RAM was being used for page cache,
>> > which is what we want, but that seems to have dropped off over time, and
>> > there's currently actually like 12GB of totally unused RAM.
>> >
>> >
>> > http://s76.photobucket.com/user/kgoesspb/media/db1-mem-historical.png.html
>> >
>> > Is that expected? Is there a setting we need to tune for that? We have
>> > 400GB of databases on this box, so I know it's not all fitting in that
>> > 49.89GB.
>>
>> could be a numa issue. Take a look at:
>>
>> http://frosty-postgres.blogspot.com/2012/08/postgresql-numa-and-zone-reclaim-mode.html
>>
>> merlin
> Good suggestion, but nope, that ain't it:
>
> $ cat /proc/sys/vm/zone_reclaim_mode
> 0

Could it just be your dataset isn't any bigger than what's being used?
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