How to monitor Linux performance using SAR ?

SAR

  a. Monitor system real time performance (CPU, Memory, I/O, etc)

  b. Collect performance data in the background and do analysis on the historical data to identify bottlenecks

Sar is part of the sysstat package.

Features

• Collective CPU usage
• Individual CPU statistics
• Memory used and available
• Swap space used and available
• Overall I/O activities of the system
• Individual device I/O activities
• Context switch statistics
• Run queue and load average data
• Network statistics
• Report sar data from a specific time

Example

Display the system CPU statistics 3 times (with 1 second interval)

sar -b” command reports I/O statistics.

“1 3″ indicates that the sar -b will be executed for every 1 second for a total of 3 times.

$ sar -b 1 3

Linux 2.6.18-194.el5PAE (dev-db)     03/26/2011      _i686_  (8 CPU)

01:56:28 PM       tps      rtps      wtps   bread/s   bwrtn/s

01:56:29 PM    346.00    264.00     82.00   2208.00    768.00

01:56:30 PM    100.00     36.00     64.00    304.00    816.00

01:56:31 PM    282.83     32.32    250.51    258.59   2537.37

Average:       242.81    111.04    131.77    925.75   1369.90