How to use SAR to troubleshoot linux box and generate reports.

SAR stands for System Activity Report, as its name suggest sar command is used to collect, report & save CPU, Memory, I/O usage in Unix like operating system. SAR command produce the reports on the fly and can also save the reports in the log files as well.
Now a days sar includes in general Linux installation. You can check if sar is installed by executing following command.


rpm -qa | grep sysstat


Incase if sar is not installed you can use following command or RPM package to install it.

yum install sysstat


Sysstat data collection is doing by sadc (system activity data collector). It saves the reports in log file “/var/log/sa/saDD”  where DD represents Current day and already existing files will be archived.


[root@localhost ~]# systemctl start sysstat
[root@localhost ~]# systemctl enable sysstat


It collects the data every 10 minutes and generate its report daily. Below crontab file is responsible for collecting and generating reports.


Generating CPU Report on the Fly 5 times every 2 seconds.


[root@localhost ~]# sar 2 5 

Linux 3.10.0-123.el7.x86_64 (localhost.localdomain)     Monday 26 October 2015     _x86_64_    (2 CPU) 01:43:55  EDT     CPU     %user     %nice   %system   %iowait    %steal     %idle 01:43:57  EDT     all      0.00      0.00      0.25      0.00      0.00     99.75 01:43:59  EDT     all      0.00      0.00      0.00      0.00      0.00    100.00 01:44:01  EDT     all      0.00      0.00      0.25      0.00      0.00     99.75 01:44:03  EDT     all      0.00      0.00      0.25      0.25      0.00     99.50 01:44:05  EDT     all      0.00      0.00      0.00      0.00      0.00    100.00 Average:        all      0.00      0.00      0.15      0.05      0.00     99.80 [root@localhost ~]#

Generating Memory Usage report using -r

Reading SAR log file using -f

[root@localhost ~]# sar -r -f /var/log/sa/sa26

Create Graphs using KSAR tool

You need download KSAR tool to create graphs using /var/log/sa/sar* files

https://sourceforge.net/projects/ksar/

You need to convert time format in sar file before loading to sar you can do it by using following commands

cd /var/log/sa

LC_TIME="POSIX" sar -A -f sa08 > /tmp/sar.data.txt

now download sar.data.txt file and load it in to KSAR