Monitoring system resource usage and statistics on Ubuntu

figuring out what caused the server to go down this morning

Basically, i'm looking for answers to these:

  • Why did the server go down?
  • What process was taking so many resources that the server crashed?

CPU utilization history and logs with System Activity Reporter (SAR)

The sar command can give you CPU utilization history. It's a part of a software bundle called sysstat which you'll need to install on Debian/Ubuntu

# install
sudo apt install -y sysstat

# enable data collection
# Set ENABLED="true" in "/etc/default/sysstat"
sudo sed -i 's/ENABLED="false"/ENABLED="true"/g' /etc/default/sysstat

# change the collection interval from every 10 minutes to every 2 minutes.
sudo sed -i 's/5-55\/10/*\/2/g' /etc/cron.d/sysstat

# restart sysstat for the change to take effect and data collection to start working
sudo service sysstat restart

# check cpu utilization

The logs are saved in /var/log/sa/

By default only activity of last 7 days are saved, to change it, please check:


To check for example yesterday (05 October):

sar -P ALL -f /var/log/sa/sa05

You can script the above for configuring all new Ubuntu machines to have sysstat from the get go

sudo apt-get install sysstat -y
sudo sed -i 's/ENABLED="false"/ENABLED="true"/g' /etc/default/sysstat
sudo sed -i 's/5-55\/10/*\/2/g' /etc/cron.d/sysstat
sudo service sysstat restart

Real-time CPU and memory usage

  • htop and top. htop is definitely an improvement over top



Please note that this site and the posts on it are, and will always be, a work in progress. If i waited for perfection, i’d never get anything done.