ServerNet Cluster Manual

Upgrading a ServerNet Cluster
ServerNet Cluster Manual—520575-003
4-60
Steps for Merging Two Star Topologies to Create a
Split-Star Topology
Steps for Merging Two Star Topologies to Create a Split-Star
Topology
To merge two clusters that use one cluster switch per fabric to create a split-star
topology:
1. Decide which nodes will occupy the two star groups of the split-star topology. You
can use Table 4-17 to record the nodes that will belong to each star group of the
split-star topology. This form accommodates information about the nodes and
cluster switches before and after the upgrade.
2. Record information about the cluster switches that will serve the two star groups of
the split-star topology. You can use Table 4-18 to plan for the cluster switches.
Make copies of this form to record before and after information.
Caution. Do not connect the four-lane link until you are instructed to do so by the Add Switch
guided procedure. Connecting the four-lane link between two cluster switches running the
T0569AAA configuration can cause an outage on every node in the cluster if the NNA Version
is 5. (FCO 39746B replaced Version 5 NNAs with NNA Version 22.) You might need to power
cycle each node to recover from this outage.
Outages can occur because the cluster is unprotected by the neighbor-checking logic if cluster
switches running the T0569AAA configuration are connected. Connecting two cluster switches
running the T0569AAA configuration can create an invalidly configured split-star topology in
which ServerNet packets sent by nodes 1 through 8 to nodes 9 through 16 loop indefinitely
between the two cluster switches.