On Thu, 13 Dec 2007, Ow Mun Heng wrote:
I'm using centos 5 as the OS so, there's no fancy dtrace to look at which processes is causing my disks to thrash.
Does plain old top show you anything interesting? If you hit 'c' after starting it you'll get more information about the postgres processes in particular.
1 OS disk [hda] rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util hda 98.60 14.69 121.98 15.08 1775.02 2908.29 34.17 47.53 551.67 7.29 99.95
The funny thing here is that both the writes and reads are very high compared to the other disks. That rules out most of what I go looking for when there's run-away activity. Many common causes do almost all reads (i.e. some filesystem crawler like updatedb running) or almost all writes (loggers gone wild!). Swapping might do both, so consider mine a second vote to correlate this with vmstat output.
-- * Greg Smith gsmith@xxxxxxxxxxxxx http://www.gregsmith.com Baltimore, MD ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
