Alvaro, Thanks for your reply. I believe that the only possibility is autovacum activity I will check that. Anyway what puzzles me is that the throughput does not increase like i might expect if there where high VACUUM activity, only the WAIT TIME and thus the UTILIZATION. Is like if the disk/filesystem gets slower during one hour or so...
On Fri, Jul 26, 2013 at 5:27 PM, Alvaro Herrera <alvhe...@2ndquadrant.com>wrote: > German Becker escribió: > > Hi list, > > > > I am running Postgres 9.1 on Ubuntu 12.04. I have a dedicated disk for > > pg_xlog, using ext4 filesystem with journaling in writeback mode > > During high load times, the disk usage is arround 40%. The IO write time > is > > constant at about 3ms. On certain occasions roughly once in 15 days, the > > IO write time goes up to about 10ms. This makes the disk usage go up to > > almost 100%, probably saturation, and the INSERTS DELETES UPDATES run > > considerable slower than normal.This lasts for about 2 hours and then the > > latency goes back to 3ms and everything is normal again. > > Has anyone seen this behavior? What could be causing the increase in > > latency? > > Can you correlate these episodes with autovacuum activity? Or perhaps > backups are being taken (maybe a new base backup is taken every 15 > days)? > > -- > Álvaro Herrera http://www.2ndQuadrant.com/ > PostgreSQL Development, 24x7 Support, Training & Services >
