Fixing invalid system activity with sar

Sometimes sar can return errors complaining about an invalid system activity file such as:

Invalid system activity file: /var/log/sysstat/sa03

It can be resolved by:

rm /var/log/sysstat/sa03
/etc/init.d/sysstat start
* Starting the system activity data collector sadc [ OK ]

Now if you rerun sar, you should see the stats output starting to populate:

Linux 3.2.0-83-virtual (web01) 04/03/2014 _x86_64_ (8 CPU)