Why does iostat -x sometimes show incorrect values on Red Hat Enterprise Linux 4 and 5 systems ?

Issue

• When running iostat with the "-x" option some of the values can be unrealistically large, for example:

    $ iostat -dx
    Linux 2.6.9-78.EL (hostname)        01/05/09

    Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
    sda          2.52   2.23 3006561.74  1.54  295.82   30.19   147.91    15.10     0.00     0.06    0.00   0.00   1.89

    $ iostat -dx
    Linux 2.6.9-78.EL (hostname)        01/05/09

    Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
    sda 0.00 0.00 18889465927081071214592.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

The value for "r/s" changed from 3006561.74 to 18889465927081071214592.00.