Hi, We have a front-end server taking care of Nginx, memcached and Postgresql. Last night the postgres daemon crashed (traffic was very low at that time) with the following error: 2010-12-20 03:34:30 EST DETAIL: Failed system call was shmget(key=5432001, size=1124474880, 03600). 2010-12-20 03:34:30 EST HINT: This error usually means that PostgreSQL's request for a shared memory segment exceeded available memory or swap space. To reduce the request size (currently 1124474880 bytes), reduce PostgreSQL's shared_buffers parameter (currently 131072) and/or its max_connections parameter (currently 963). Front-end server has 4GB ram. The reason why max_connections and shared buffers were so high was that we recently had to run the server without a connection pooler because our connection pooler died. We have since fixed the connection pooler, and last night it was running normally. I didn't think there would side effects to leaving Postgresql configured with 1024MB shared_buffers and 963 max_connections Anyways, I have now reduced the shared_buffers and max_connections to : 256MB and 140 respectively. Our connection pooler is configured to establish no more than 128 connections at a time so 140 max_connections will be fine. The problem is that I am not sure what is the ideal shared_buffers settings should be. How should we properly "guesstimate" the correct value for shared_buffers? I saw some people using the values max_connections * 16KB, so should I reduce it to 2.3MB ? Also, was this error caused by kernel.shmmax value being too low? (I just noticed this: Failed system call was shmget(key=5432001, size=1124474880, 03600). Thanks, -- Ben -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
