54 An Introduction to the New IBM Eserver pSeries High Performance Switch
Figure 2-34 JTAG access to HPS components
The HMC as fabric manager
Currently, fnmd and hrdw_svr are restricted to running on an HMC. However, that may not be
a permanent condition. There has been talk of allowing these packages to be migrated to a
CSM master. In such a situation, there would likely exist conditions in which the HMC itself
was no longer needed. Until such time, client access for CIMOM,low-level commands (llcmd),
and vterm sessions continue to be provided by hdwr_svr through TCP port 9734.
The most important time for the fabric manager is during initialization. Once all of the nodes
are initialized and brought onto the switch network, the fabric manager can be brought down.
Recovery operations will fail while the fabric manager is down. However, reboots should not
leave a node off of the switch.
In other words, once running, the switch can continue should the HMC fail.
2.6 FNM communication
FNM communication is the API used by the Federation Network Manager daemon (fnmd) to
perform all operations required for management of the pSeries HPS. Multiple FNM daemons
will be running on HMC. This is normal and is to facilitate the various functions of FNM
communication. The various commands are issued through hrdw_svr as shown in
Figure 2-35 on page 55.
Note: The fnmd and Hypervisor functions replace the equivalent functions of the fault
service worm from PSSP’s CSS.
Important: Recovery is required for an MP_DOWN or MP_FAIL error. Five such errors
logged against the same link will render that link fenced. Should a link become fenced, the
only recovery will be to logically power cycle the CEC.