Fabric Manager Users Guide, Version 6.1, Revision A - QLogic

2–Advanced Fabric Manager Capabilities
Performance Manager
PM Sweeps
PA Images
NOTE:
Some Ports do not support a PMA (such as un-managed Switch Port 0) also
for some devices the PM may be told to avoid the PMA by the FM
configuration. Such devices are omitted from all Groups.
The PM performs regular sweeps of the fabric to get and analyze PMA counters
for all the devices in the fabric. The PM Sweep Interval is configurable using the
Pm.SweepInterval parameter. If set to 0, PM automatic sweeps are disabled. If
Pm.SweepInterval is not specified, the default is 0, therefore when an upgrade
and continue using the old configuration file is accomplished, the PM engine will
be disabled.
For fabrics with devices which support 64-bit counters, the value can be set much
larger. Larger values will reduce the frequency at which data is gathered and
decrease OS jitter and overhead on the Fabric Manager node. Smaller values will
increase the frequency of sweeps (and the frequency at which fresh data is
available to tools like iba_report, iba_top, iba_rfm, iba_paquery, and so
on).
Each sweep typically involves only a few packets per node, so even at faster
sweep rates, overhead per node is quite modest. Note that at full QDR speeds a
32-bit data movement counter can overflow in slightly over four seconds. However
64-bit counters take over a hundred years to overflow.
See the QLogic FastFabric User Guide for more information about tools which can
query and/or analyze the data available from the PM (iba_report, iba_top,
iba_rfm, iba_paquery, and so on).
The PM is constantly monitoring the port counter information in the fabric using
periodic sweeps. Each sweep gathers the port counters in the fabric and performs
reduction and summary calculations of the data to provide group level information
in the PA.
Each sweep is stored as a PA image. An image is a historical representation of
the fabric data, a time slice. The number of images stored in the PA is finite, with
the oldest images being replaced with new ones as resources dictate. The images
are identifiable and may be retrieved for examination as long as they still exist in
the PA (if they have not been replaced with a newer image due to resource
constraints).
The recent history is retained in the memory of the PM. The amount of recent
history is configurable using Pm.TotalImages.
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