OpenVMS Cluster Systems - OpenVMS Systems - HP

Cluster Troubleshooting
C.10 Diagnosing Port Failures
Configuration 4: Example C–4 shows the possible combinations of two pairs of
crossed cables that cause loopback datagrams to fail on both computers in the
cluster but that allow communications. No entry stating that cables are crossed
is made in the error log of either computer.
Example C–4 Crossed Cables: Configuration 4
T x x R T = = R
R = = T R x x T
LOC REM LOC REM
Configuration 5: Example C–5 shows the possible combinations of four pairs of
crossed cables. In each case, loopback datagrams fail on the computer that has
only one crossed pair of cables. Loopback datagrams succeed on the computer
with both pairs crossed. No communications are possible.
Example C–5 Crossed Cables: Configuration 5
T x x R T x = R T = x R T x x R
R x = T R x x T R x x T R = x T
LOC REM LOC REM LOC REM LOC REM
If all four cable pairs between two computers are crossed, communications
succeed, loopback datagrams succeed, and no crossed-cable message entries are
made in the error log. You might detect such a condition by noting error log
entries made by a third computer in the cluster, but this occurs only if the third
computer has one of the crossed-cable cases described.
C.10.7 Repairing CI Cables
This section describes some ways in which Compaq support representatives can
make repairs on a running computer. This information is provided to aid system
managers in scheduling repairs.
For cluster software to survive cable-checking activities or cable-replacement
activities, you must be sure that either path A or path B is intact at all times
between each port and between every other port in the cluster.
For example, you can remove path A and path B in turn from a particular port to
the star coupler. To make sure that the configuration poller finds a path that was
previously faulty but is now operational, follow these steps:
Step Action
1 Remove path B.
2 After the poller has discovered that path B is faulty, reconnect path B.
Cluster Troubleshooting C–23