ServerNet Cluster Manual

Upgrading a ServerNet Cluster
ServerNet Cluster Manual—520575-003
4-66
Fallback for Merging Clusters to Create a Split-Star
To p ol ogy
Fallback for Merging Clusters to Create a Split-
Star Topology
This fallback procedure divides a split-star topology into two ServerNet clusters that
support no more than eight nodes each. In this scenario, you separate the clusters into
two individual logical clusters with only one switch per fabric for each cluster. (Each
star group of the split-star topology is a logical cluster.)
1. Select one of the star groups for a complete shutdown of ServerNet cluster
services. You can use the star group with the fewest nodes or the star group that is
least critical to your application.
2. In all nodes, stop any applications that depend on ServerNet cluster connectivity to
the nodes in the other star group.
3. In all nodes of the star group selected in Step 1:
a. Stop any applications that depend on ServerNet cluster connectivity to nodes
within that star group.
b. Abort the Expand-over-ServerNet lines to all nodes in the other star group.
c. Use the SCF STOP SUBSYS $ZZSCL command to ensure an orderly
shutdown of ServerNet communications on that star group.
4. In all nodes of the other star group, abort all Expand-over-ServerNet lines to all
nodes in the star group selected in Step 1.
5. Disconnect the four-lane links for each fabric to form two physically independent
clusters.
Note. Disconnecting ports 8 through 11 prevents unnecessary neighborhood-error-check
alarms generated on all system consoles. These alarms are generated because the
T0569AAA firmware and configuration are not supported in a split-star topology.
T0569AAB firmware and configuration are mandated on all cluster switches that are
connected in a split-star topology.