OpenVMS Cluster Systems - OpenVMS Systems - HP

Cluster Troubleshooting
C.10 Diagnosing Port Failures
C.10.4 Verifying Virtual Circuits
To diagnose communication problems, you can invoke the Show Cluster utility
using the instructions in Table C–4.
Table C–4 How to Verify Virtual Circuit States
Step Action What to Look for
1 Tailor the SHOW CLUSTER report by entering the SHOW
CLUSTER command ADD CIRCUIT,CABLE_STATUS. This
command adds a class of information about all the virtual
circuits as seen from the computer on which you are running
SHOW CLUSTER. CABLE_STATUS indicates the status of the
path for the circuit from the CI interface on the local system to
the CI interface on the remote system.
2 Run SHOW CLUSTER from each active computer in the
cluster to verify whether each computer’s view of the failing
computer is consistent with every other computer’s view.
WHEN... THEN...
All the active computers have
a consistent view of the failing
computer
Only one of several active
computers detects that the
newcomer is failing
The problem may be in
the failing computer.
That particular computer
may have a problem.
Primarily, you are checking whether there
is a virtual circuit in the OPEN state to the
failing computer. Common causes of failure
to open a virtual circuit and keep it open are
the following:
• Port errors on one side or the other
• Cabling errors
• A port set off line because of software
problems
• Insufficient nonpaged pool on both sides
• Failure to set correct values for
the SCSNODE, SCSSYSTEMID,
PAMAXPORT, PANOPOLL,
PASTIMOUT, and PAPOLLINTERVAL
system parameters
If no virtual circuit is open to the failing
computer, check the bottom of the SHOW
CLUSTER display:
• For information about circuits to the
port of the failing computer. Virtual
circuits in partially open states are
shown at the bottom of the display. If
the circuit is shown in a state other
than OPEN, communications between
the local and remote ports are taking
place, and the failure is probably at
a higher level than in port or cable
hardware.
• To see whether both path A and path B
to the failing port are good. The loss of
one path should not prevent a computer
from participating in a cluster.
C.10.5 Verifying CI Cable Connections
Whenever the configuration poller finds that no virtual circuits are open and
that no handshake procedures are currently opening virtual circuits, the poller
analyzes its environment. It does so by using the send-loopback-datagram facility
of the CI port in the following fashion:
1. The send-loopback-datagram facility tests the connections between the CI
port and the star coupler by routing messages across them. The messages are
called loopback datagrams. (The port processes other self-directed messages
without using the star coupler or external cables.)
C–20 Cluster Troubleshooting