I have a postgresql server running on a small linode partition. It is running a web app for a site which gets on average 0 users / minute (it has not launched yet). At one point, I loaded up the database with a lot of data, to do a stress test. I have since deleted the data and now have a few hundred megabyte DB just sitting there without anyone asking anything of it.
The linode server is reporting an average IO rate of 2.6k blocks a second. I ran
pidstat -d 10 90 and figured out that the culprit was postgres:
Average: PID kB_rd/s kB_wr/s kB_ccwr/s Command Average: 28836 1251.31 0.00 0.00 postgres
Further digging shows that approximately once every three minutes postgresql decides to do some heavy lifting (a short burst of reading at 21mb/s).
I know the bare minimum when it comes to DB administration and have an issue. My research unearthed things like
VACUUMing and such. However, I am not sure what is happening, why, and how to stop it. There is absolutely no load on this machine. Can anyone point me in the right direction?