View Past Performance Data With sar

sysstat stores past data in the directory

/var/log/sa - for RHEL based OS
/var/log/sysstat - for Debian based OS

Each day log files are stored in a file with the respective date.

sa01 - log file for day 1
sa31 - log file for day 31

To view logs for day 9, run

sar -f /var/log/sa/sa09

If you want to see entries during a specific time, you can use

sar -f /var/log/sa/sa09 -s hh:mm:ss

Example

You can specify end time with -e option

If you want to see IO data, use -b option

sar -f /var/log/sa/sa09 -b