VMS Help
SET, CLUSTER, /EXPECTED_VOTES
*Conan The Librarian (sorry for the slow response - running on an old VAX)
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Sets the total expected votes in the OpenVMS Cluster to a value
that you specify or, if no value is specified, sets the total
votes to a value determined by the system.
Requires OPER (operator) privilege.
Format
SET CLUSTER/EXPECTED_VOTES[=value]
value
Specifies the total number of expected votes in the cluster.
The SET CLUSTER/EXPECTED_VOTES command enables you to adjust the
total number of expected votes in the cluster. Set this value
equal to the number of votes contributed by each node plus the
number of votes contributed by the cluster quorum disk. The
system will automatically calculate the value of the cluster
quorum from the total number of expected votes in the cluster.
You can specify the expected total votes value as part of the
SET CLUSTER/EXPECTED_VOTES command string. If you enter the
command without specifying a value for expected votes, the system
calculates the value for you, using the following formula:
EXPECTED_VOTES=(NODE1_VOTES+NODE2_VOTES+...)+QUORUM_DISK_VOTES
NODEn_VOTES is the value of the system parameter VOTES for each
node in the cluster and QUORUM_DISK_VOTES is the value of the
system parameter QDSKVOTES.
When you enter the SET CLUSTER/EXPECTED_VOTES command without
specifying a value, the system assumes that all nodes that are
expected to be in the cluster are currently members.
In general, you use the SET CLUSTER/EXPECTED_VOTES command only
when a node is leaving the cluster for an extended period of
time. Under normal circumstances, quorum is not reduced when a
node leaves the cluster, because it is assumed that the node may
be rebooted and rejoin the cluster. If a node is removed and is
unable to rejoin the cluster within a reasonable period of time
(for example, if a node crashes due to a hardware problem and
cannot rejoin the cluster for several days), the quorum for the
cluster can safely be reduced by lowering the total expected
votes until that node rejoins.
The purpose of a cluster quorum is to eliminate any possibility
of the cluster partitioning into separate clusters and
simultaneously accessing the same resources (such as disks).
If the sum of the votes for all members of the cluster is smaller
than the cluster quorum, all nodes will block activity until new
nodes join to increase the vote total. Lowering the quorum value
(by reducing the value of the total expected votes) when one or
more nodes leave the cluster for long periods of time reduces
this possibility.
Note that no matter what value you specify for the SET
CLUSTER/EXPECTED_VOTES command, you cannot increase quorum to
a value that is greater than the number of the votes present,
nor can you reduce quorum to a value that is half or fewer of the
votes present.
When you enter the SET CLUSTER/EXPECTED_VOTES command, either
with or without an expected votes value specified, the system
responds with a message indicating the new value that was
actually set. Note that you need to enter this command only on
one node in the cluster, because the new value for total expected
votes is propagated through the cluster. This new expected votes
value should then be stored in the system parameter EXPECTED_
VOTES on each node, so that it remains in effect after the nodes
reboot.
When a node that was previously a member of the cluster is
ready to rejoin, you should increase the system parameter
EXPECTED_VOTES to its original value before bringing the node
back to the cluster. Note that you do not need to use the SET
CLUSTER/EXPECTED_VOTES command to increase the number of expected
votes, because the expected votes value will be increased
automatically when the node rejoins the cluster.
1.$ SET CLUSTER/EXPECTED_VOTES
The SET CLUSTER command in this example instructs the system
to calculate the total expected votes value for you, because
no value is specified as part of the command string. The system
uses the NODEn_VOTES + QUORUM_DISK_VOTES formula.
2.$ SET CLUSTER/EXPECTED_VOTES=9
The SET CLUSTER command in this example sets the total expected
votes to 9, which is the value specified in the command string.
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