I'm using Linode to host a Wordpress blog with an eCommerce plugin named 'Shopp'.
I moved the site just a few days ago from a previous shared hosting account (with less resources than the Linode VPS).
The problem did not occur on the previous host.
Every few hours (around 10-11 hours, varies) I can see a peak in bandwidth ('normal' traffic is around 400k-600k/s) of 1.1mb/s. At the same time I can see that I/O and SWAP also peaks to between 10k-20k which causes the server to basically lock down. It locks for around 30 to 40 minutes or until I reboot it.
I've turned on the mysql slow query log to see if I can get any clues there, but unfortunately all the queries it logged seemed normal (things like 'select column, from table1 where id=1', another example that caught my eyes on the slow query log is 'set names utf8').
How can I investigate what is causing this issue? Is there a way to know for sure if the problem originates from the db, or maybe one of the php files on the server?
What's the best way to continue from here?
P.S: Running Ubuntu 10.04, 32bit, latest mysql/php/apache2 and using Linode 1024