220.127.116.11. The sar command
sarcommand produces system utilization reports based on the data collected by
sadc. As configured in Red Hat Enterprise Linux,
saris automatically run to process the files automatically collected by
sadc. The report files are written to
/var/log/sa/and are named
<dd>is the two-digit representations of the previous day's two-digit date.
saris normally run by the
sa2script. This script is periodically invoked by
cronvia the file
sysstat, which is located in
/etc/cron.d/. By default,
sa2once a day at 23:53, allowing it to produce a report for the entire day's data.
The format of a
sarreport produced by the default Red Hat Enterprise Linux configuration consists of multiple sections, with each section containing a specific type of data, ordered by the time of day that the data was collected. Since
sadcis configured to perform a one-second measurement interval every ten minutes, the default
sarreports contain data in ten-minute increments, from 00:00 to 23:50.
Each section of the report starts with a heading describing the data contained in the section. The heading is repeated at regular intervals throughout the section, making it easier to interpret the data while paging through the report. Each section ends with a line containing the average of the data reported in that section.
Here is a sample section
sarreport, with the data from 00:30 through 23:40 removed to save space:
00:00:01 CPU %user %nice %system %idle 00:10:00 all 6.39 1.96 0.66 90.98 00:20:01 all 1.61 3.16 1.09 94.14 … 23:50:01 all 44.07 0.02 0.77 55.14 Average: all 5.80 4.99 2.87 86.34
In this section, CPU utilization information is displayed. This is very similar to the data displayed by
Other sections may have more than one line's worth of data per time, as shown by this section generated from CPU utilization data collected on a dual-processor system:
00:00:01 CPU %user %nice %system %idle 00:10:00 0 4.19 1.75 0.70 93.37 00:10:00 1 8.59 2.18 0.63 88.60 00:20:01 0 1.87 3.21 1.14 93.78 00:20:01 1 1.35 3.12 1.04 94.49 … 23:50:01 0 42.84 0.03 0.80 56.33 23:50:01 1 45.29 0.01 0.74 53.95 Average: 0 6.00 5.01 2.74 86.25 Average: 1 5.61 4.97 2.99 86.43
There are a total of seventeen different sections present in reports generated by the default Red Hat Enterprise Linux
sarconfiguration; some are explored in upcoming chapters. For more information about the data contained in each section, refer to the