Sar

Monitoring server resources is a crucial part of identifying any bottlenecks and possible issues on your server.

sar stands for “System Activity Reporter” and provides a wide range of metrics related to system usage, including CPU utilization, memory usage, disk I/O, network activity.

on Ubuntu, sar can be installed by following

#install sar
$ sudo apt-get install -y sysstat

# Enable data collecting
sed -i 's/false/true/g' /etc/default/sysstat

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

# Restart service
$ sudo systemctl start sysstat

sar system service

sar can be run as system service as well,

1. sudo systemctl start sysstat
2. sudo systemctl enable sysstat
3. This will add the required cron jobs so that the system data is collected accordingly. The cron jobs will be added at cat /etc/cron.d/sysstat

Command and options

sar has a lot of arguments and options and basic comman syntax is following,

$ sar -[ options ] time_interval number_of_tines_to_display

$sar --help

Full description is available in sar man page

Here are few examples,

Options	Description	output format
sar -u 2 30	-u for all CPU, 2 means that the sar command should run every 2 seconds 30 means that the command should be executed 30 times.
sar -r 2 30	-r for memory
sar -n DEV 4	-n for network interfaces, 4 means that the sar command should run every 2 seconds
sar -d	-d command to view disk I/O statistics, including IOPS	DEV       tps     rkB/s     wkB/s     dkB/s   areq-sz    aqu-sz     await     %util tps is IOPS