First install the sysstat package which includes sar:
```bash
apt-get install sysstat
```
Then run crontab -e and add the following to collect stats:
```bash
# Collect measurements at 10-minute intervals
0,10,20,30,40,50 * * * * /usr/lib/sa/sa1
# Create daily reports and purge old files
0 0 * * * /usr/lib/sa/sa2 -A
```
You now have access to IO and CPU usage history.
Use this command see the data for the 5th day of the current month:
```bash
sar -f /var/log/sysstat/sa05
```
And remember to enable collection of statistics:
```bash
sudo vim /etc/default/sysstat
```