How to deal with high IO in linux

If you are dealing with high IO wait on linux machine then you must detect which application causing this.

First use
# top

This will show list of current running applications.

Then use
# iotop
to see see only IO statistics.

If you select application with high IO then you can see what is writing/reading from disk using
# lsof -p 12345

12345 is pid name from #top or #iotop command.