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The sar command is used to sample and report various cumulative statistic counters maintained by the operating system.

SYNOPSIS

sar [-dgpu] [-n mode] [-o filename] t [n]

sar [-dgpu] [-n mode] [-e time] [-f filename] [-i seconds] [-s time]

The sar command writes to standard output the contents of selected cumulative activity counters in the operating system. The accounting system, based on the values in the count and interval parameters, writes information the specified number of times spaced at the specified intervals in seconds.

Usually system admins and DBA’s requires a link to the site where he can find the necessary informations,
Below are the links which gives more idea about the sar man pages,monitoring, analysing etc ..

sar

The sar command gathers statistical data about the system.

Though it can be used to gather some useful data regarding system performance, the sar command can increase the system load that can exacerbate a pre-existing performance problem if the sampling frequency is high. But compared to the accounting package, the sar command is less intrusive. The system maintains a series of system activity counters which record various activities and provide the data that the sar command reports. The sar command does not cause these counters to be updated or used; this is done automatically regardless of whether or not the sar command runs. It merely extracts the data in the counters and saves it, based on the sampling rate and number of samples specified to the sar command.

Easy system monitoring with SAR

Learn how to correlate user complaints with the system activity reporter (SAR) and build a performance baseline for trending purposes using SAR logs. SAR is the perfect tool for systems administrators. It captures important system performance metrics at periodic intervals .

Solaris 9 System Monitoring and Tuning

Gathering system activity data from vmstat and iostat can be a time-consuming job. You need to automate the gathering of system activity data, and the tool to use is sar. sar refers to the system activity reporter and is used to gather performance data from all the major components of the system. sar comes standard on most UNIX systems, including Solaris. sar can be enabled by uncommenting the appropriate lines in the system crontab and is described later in this section.

Tracking system performance with SAR

Sar is the “system activity report” program. In Linux, it is usually found in the sysstat package. The sysstat package includes programs and scripts to capture and summarize performance data, then produce detailed reports. This suite of programs can be very useful in tracking down performance bottlenecks and providing insight into how the system is used throughout the day.