Example Of An 8_8 Configuration - IBM RS/6000 SP Problem Determination Manual

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5.2.4 Switch Topologies
The effect of partitioning the High Performance Switch is that there is no
interference between the partitions that have been set up. Anything that
happens in one partition will have no effect on the others. If a switch fault is
generated in one partition, this will not affect the switch in the others. The fabric
of the other partitions will remain stable while the Worm daemon on the primary
node in the partition that took the switch fault will attempt to recover the switch
network in that partition. This behavior is ensured by each partition having a
different topology file that does not contain any routes that would allow traffic to
flow between partitions. As a result, nodes in one partition have no knowledge
of how to communicate with the nodes outside its own partition. The Worm
daemon on the primary node is responsible for generating the routing tables,
which it then distributes to the switch adapters on the nodes for storing in their
NVRAM.
Each partition has its own primary node, so that running
has no effect on the others. The Worm on the primary can carry out its tasks in
a completely independent manner from the other partitions.
Generating the correct routes for the partition based on the topology files that
get selected during the apply of the System Partitioning is critical to the health of
the switch in that partition.
Following is an example of how a single switch system with 16 thin nodes could
be partitioned using one of the layouts for the 8_8 configurations.
Figure 59. Example of an 8_8 Configuration
By deleting half of the routes (8 of the 16), there is no communication possible
between the two partitions. However, within the 8-way partition, there are only
two possible routes between each and every node (where previously there were
four). Halving the bandwidth in this way does have an impact on performance,
Estart
in one partition
Chapter 5. System Partitioning
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