I am just reviewing the disk IO of a XEN VM server. I stumbled across a DomU that has constant write traffic.
To narrow that traffic further down I logged in to the DomU (CentOS 5, 64 Bit) and started
iostat 5. It shows sda1 active with 130-190 Blocks written per second.
sda: Whole disk (corresponds to DRBD-device in the Dom0, consist of one LV in the Dom0) sda1: / sda2: /var sda3: LVM-PV for application data, contains one LV mounted as subdirectory on /var
I tried to find open file handles on /dev/sda1 by issuing
lsof /dev/sda1. The output of that command is empty. Whereas the output for
lsof /dev/sda2 shows lots of files, pipes, ... (as is to be expected).
How can I track down what is causing this IO?