Continuous performance monitoring with the iostat command

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The iostat command is useful for determining disk and CPU usage.

The AIX operating system maintains a history of disk activity. In the following example, the disk I/O history is disabled because the following message is displayed:
Disk history since boot not available.

The interval disk I/O statistics are unaffected by this.
To enable disk I/O history, from the command line enter smit chgsys and then select true from the Continuously maintain DISK I/O history field.

The following sample report is displayed when you run the iostat command:

# iostat 5 2

tty:      tin         tout   avg-cpu:  % user    % sys     % idle    % iowait
          0.1        102.3               0.5      0.2       99.3       0.1     

               Disk history since boot not available. 

               The interval disk I/O statistics are unaffected by this.

tty:      tin         tout   avg-cpu:  % user    % sys     % idle    % iowait
          0.2        79594.4               0.6      6.6       73.7      19.2     

Disks:        % tm_act     Kbps      tps    Kb_read   Kb_wrtn
hdisk1           0.0       0.0       0.0          0         0
hdisk0          78.2     1129.6     282.4       5648        0
cd1              0.0       0.0       0.0          0         0

The first report from the iostat command shows cumulative activity since the last reset of the disk activity counters. The second report shows activity for the first 5-second interval.