cache Memory of server

See the free command:

am 08.06.2015 um 15:13 Uhr: --active connection: 305
srvpgsql1:/opt/pgsql_data # free
total used free shared buffers cached
Mem: 12199684 8758400 3441284 1269784 231324 7139400
-/+ buffers/cache: 1387676 10812008
Swap: 6289404 0 6289404

----------------------------------------------------------------------

am 08.06.2015 um 15:53 Uhr: --active connection: 278

srvpgsql1:/opt/pgsql_data # free
total used free shared buffers cached
Mem: 12199684 8686228 3513456 1269784 232164 7164288
-/+ buffers/cache: 1289776 10909908
Swap: 6289404 0 6289404

Von: AL-Temimi, Muthana
Gesendet: Montag, 8. Juni 2015 15:24
An: pgsql-admin(at)postgresql(dot)org
Betreff: cache Memory

Hello,

we have postgresql 9.1 installed on Suse Enterprice Linux Server. The RAM is 12GB, When the concurrent connections 275 reached the cached memory on Server 5GB and when the concurrent increased into 305 increase also the cache memory 8.5GB. but when the concurrent connections decreased into for example 165 the cache memory not decreased. The question why? Did I mess something the postgresql.conf

any help will be grateful..

Best Regards

Muthana AL-Temimi
M.Sc. Informations- und Kommunikations-Systeme

Technische Universitaet Hamburg Harburg
-Rechenzentrum-
Am Schwarzenberg-Campus 3
D-21073 Hamburg

Tel.: +49.40.42878.2338
Fax.: +49.40.42793.5160
E-Mail: m(dot)al(at)tu-harburg(dot)de<mailto:m(dot)al(at)tu-harburg(dot)de>
http://www.tu-harburg.de/rzt