Merlin Moncure <mmonc...@gmail.com> wrote: > On Wed, Jul 30, 2014 at 12:51 PM, Kevin Goess <kgo...@bepress.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.
> could be a numa issue. I was thinking the same thing. The other thought was that it could be a usage pattern and/or monitoring issue. When there are transient requests for large amounts of memory, it will discard cache to satisfy those (e.g., work_mem or maintenance_work_mem allocations). If the *active* portion of the database is not as big as RAM, it might not refill right away. This could be compounded on your monitoring graphs if they summarize by taking the *average* RAM usage for an interval rather than the *maximum* usage for that interval. Intermittent spikes in usage could make it look like the RAM is unused if you are averaging; personally, I would prefer to use maximum for a metric like this. Many monitoring systems allow you to choose. -- Kevin Grittner EDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
