ServerNet Cluster Manual

Upgrading a ServerNet Cluster
ServerNet Cluster Manual—520575-003
4-73
Steps for Merging Three Star Topologies to Create a
Tr i-Star Top ology
Steps for Merging Three Star Topologies to Create a Tri-Star
Topology
The following steps describe how to use the Add Switch guided procedure to merge
three clusters that use one cluster switch per fabric to create a tri-star topology:
1. Start with three functioning ServerNet clusters that use one cluster switch per
fabric.
2. Decide the configuration tags to be used by the cluster switches in each cluster
when they are combined in the tri-star topology. During the upgrade, the Add
Switch guided procedure prompts you for the configuration tag. You can use
Table 4-21 on page 4-74 to record this information. Table 4-3 on page 4-5 shows
the supported configuration tags.
Caution. Do not connect the two-lane links for the tri-star topology until the Add Switch guided
procedure instructs you to do so. Connecting the two-lane links between 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. To check the running configuration, see Checking the
Revisions of the Running Firmware and Configuration on page 4-11.
Note. If you are starting with one cluster that uses the star topology and another cluster
that uses the split-star topology, see Steps for Merging a Split-Star Topology and a Star
Topology to Create a Tri-Star Topology on page 4-82.