I randomly get latency/performance problems even with very simple queries, for example fetching a row by primary key from a small table. Since I could not trace it back to specific queries, I decided to give LatencyTOP (http://www.latencytop.org/) a go. Soon after running a couple of queries, I saw this in latencytop whilst a query was hanging in postgres: Cause Maximum Percentage Writing a page to disk 19283.9 msec 99.7 the disk configuration is as follows: RAID controller: LSI MegaRAID 9261 tablespace is on a dedicated RAID10 volume, xlog on its own RAID1 and another disk for temporary data. Volumes are mounted with noatime,errors=remount-ro. This are the sysctl.conf changes I made (machine has 48GB memory) kernel.shmmax = 25344188416 kernel.shmall = 6187546 vm.swappiness = 0 vm.overcommit_memory = 2 vm.dirty_background_ratio = 1 vm.dirty_ratio = 2 vm.zone_reclaim_mode = 0 Maybe someone has seen this before and can give me some advice. Adrian -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
