Monitoring Linux Server Usage With Sar

A simple way to monitor server resource usage is with sar.  The following simple shell script sar.sh will monitor cpu, memory, network, and disk every 10 seconds and write each to a separate log file which can be easily imported into a spreadsheet for charting.

Script

# Run sar every 10 seconds until stopped
# cpu
sar -u 10  > sar.cpu.log &
# free memory
sar -r 10  > sar.freememory.log &
# disk total
sar -b 10  > sar.disk.log &
# network by device
#    - Note that you need to filter by the adaptor in use.  
#    - Run "sar -n DEV 10" to see which adaptor is being used
sar -n DEV 10 |grep eth1 > sar.network.log &

Output

The cpu log file shows user and system CPU % utilization:

03:07:55 PM     CPU     %user     %nice   %system   %iowait    %steal     %idle

03:08:55 PM     all     73.99      0.00      2.43      0.21      0.00     23.37

03:09:55 PM     all     81.79      0.00      2.67      0.21      0.00     15.34

03:10:55 PM     all     82.29      0.00      2.68      0.17      0.00     14.86

The free memory log file shows how much memory is free and used:

03:07:55 PM kbmemfree kbmemused  %memused kbbuffers  kbcached  kbcommit   %commit

03:08:55 PM 110106128  88246712     44.49    356468  42850352  30363972      7.61

03:09:55 PM 110053452  88299388     44.52    356472  42879192  30371420      7.61

03:10:55 PM 109989584  88363256     44.55    356484  42914152  30372688      7.61

The disk log file shows read and write transfers per second and bytes read and written per second

03:07:55 PM       tps      rtps      wtps   bread/s   bwrtn/s

03:08:55 PM   7889.59      0.00   7889.59      0.00  58582.09

03:09:55 PM   8454.59      0.00   8454.59      0.00  62458.76

03:10:55 PM   8456.30      0.00   8456.30      0.00  62645.15

03:11:55 PM   7257.61      0.00   7257.61      0.00  57384.76

The network log file shows packets received and transmitted per second and bytes received and transmitted per second.

03:00:01 PM     IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s

03:08:55 PM      eth1   3285.46   2965.12    956.75   1824.97      0.00      0.00      1.05

03:09:55 PM      eth1   3640.33   3307.06   1053.38   2074.92      0.00      0.00      1.14

03:10:55 PM      eth1   3617.67   3283.23   1047.62   2061.22      0.00      0.00      1.65

03:11:55 PM      eth1   2917.34   2657.74    842.35   1686.10      0.00      0.00      1.38

03:12:55 PM      eth1   3859.74   3502.98   1119.06   2194.43      0.00      0.00      1.15