How To Use Sar To Monitor System Performance
Table of Contents
- Prerequisites
- Installing the sysstat package
- Launching the sysstat service
- Using sar to get system performance statistics
- Conclusion
sar
is a multi-purpose system performance monitoring utility which is part of the sysstat
package. With sar
, you can collect, report, or save various types of system activities such as CPU, RAM, I/O, Disk usage, etc.
In this article, we will be covering the process of installing and using sar
to monitor system performance.
Prerequisites
- An instance running CentOS 7 x64.
- A sudo user.
Installing the sysstat package
In order to use sar
, you need to install the sysstat
package. However, it is a good practice to first update your system’s packages if you haven’t done so in a while.
sudo yum update
sudo shutdown -r now
Download and install the latest stable version of sysstat
from its official website:
cd ~
wget http://pagesperso-orange.fr/sebastien.godard/sysstat-11.2.0-1.x86_64.rpm
sudo yum install sysstat-11.2.0-1.x86_64.rpm
Launching the sysstat service
sudo systemctl enable sysstat
sudo systemctl start sysstat
Using sar to get system performance statistics
In short, the usage of the sar
command is:
sar [ options ] [ <interval> [ <count> ] ]
The options of sar
cover every nook and corner of the system, main options include:
-B Paging statistics
-b I/O and transfer rate statistics
-d Block devices statistics
-F [ MOUNT ] Filesystems statistics
-H Hugepages utilization statistics
-I { <int> | SUM | ALL | XALL } Interrupts statistics
-m { <keyword> [,...] | ALL } Power management statistics
-n { <keyword> [,...] | ALL }
-q Queue length and load average statistics
-R Memory statistics
-r [ ALL ] Memory utilization statistics
-S Swap space utilization statistics
-u [ ALL ] CPU utilization statistics
-v Kernel tables statistics
-W Swapping statistics
-w Task creation and system switching statistics
-y TTY devices statistics
For the purpose of this tutorial, we will be only covering some of the most common usage cases for sar
.
Display the CPU performance for 4 times with the interval of 1 second:
sar 1 4
OR
sar -u 1 4
By default, sar
will display the CPU performance report if no parameters were specified.
Output the CPU performance statistics once per second until you press Ctrl-C to cancel:
sar 1
In this example, only the interval is specified, the number of repetitions is not.
Show performance statistics for CPU (-u), memory (-r), swap space (-S), and I/O (-d):
sar -urSbd 1
Show performance statistics for the network interface:
sar -n DEV 1
Save the statistics into a specified file ~/sar.log:
sar -u -r -o ~/sar.log 1
Conclusion
sar
is a versatile command, only a few of its usage examples are mentioned in this article. You can learn more about it by inputting sar -h
or visiting its official home page.
Thank you for reading.
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