During booting my Debian today, I noticed a warning message raised against sysstat and I went about trying to solve it.
Sysstat includes monitoring tools such as mpstat and iostat which is like vmstat and they are handy to have. Anyhoo, here are the steps
1/ Open up /etc/default/sysstat in your favourite editor of your choice and edit ENABLED from false to true
2/ Then start sysstat
# /etc/init.d/sysstat start
3/ Check if you have
/var/log/sysstat/ directory if not create one.
4/ Then run
sar -A after 5min to see if data has been collected