Counter sizes and counter wrapping

The mmpmon command may be run continuously for extended periods of time. The user must be aware that counters may wrap.

This information applies to the counters involved:

The statistical counters used for the io_s and fs_io_s requests are maintained by GPFS at all times, even when mmpmon has not been invoked. It is suggested that you use the reset request prior to starting a sequence of io_s or fs_io_s requests.
The bytes read and bytes written counters are unsigned 64-bit integers. They are used in the fs_io_s and io_s requests, as the _br_ and _bw_ fields.
The counters associated with the rhist requests are updated only when the request histogram facility has been enabled.
The counters used in the rhist requests are unsigned 64-bit integers.
All other counters are unsigned 32-bit integers.