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clu_quorum(8)
NAME
clu_quorum - Configure or delete a quorum disk, or adjust quorum disk
votes, member node votes, or expected votes.
SYNOPSIS
/usr/sbin/clu_quorum [-f] [-v]
/usr/sbin/clu_quorum [-f] -d add device-name qdisk-votes
/usr/sbin/clu_quorum [-f] -d adjust qdisk-votes
/usr/sbin/clu_quorum [-f] -d remove
/usr/sbin/clu_quorum [-f] -m cluster-member member-votes
/usr/sbin/clu_quorum [-f] -e expected-votes
FLAGS
-f Force the specified action. Use the clu_quorum -f command to view
quorum data for a member that is down. Use the -f flag with other
flags when a previous clu_quorum command indicates that the
requested action failed because a cluster member was down.
-v Display additional quorum information.
-d add device-name qdisk-votes
-d adjust qdisk-votes
-d remove
Configure, remove, or adjust the votes of, the quorum disk.
Specify either 0 or 1 for qdisk-votes. Specify device-name as a
device special file name (for example, /dev/disk/dsk5 or dsk5).
-m cluster-member member-votes
Adjust the votes of the specified member. Identify the cluster-
member by its member ID or hostname. Specify either 0 or 1 for
member-votes.
-e expected-votes
Adjust expected votes throughout the cluster. The value you
specify for expected-votes should be the sum total of the node
votes assigned to all members in the cluster, plus the quorum
disk vote, if any. The clu_quorum command does not allow you to
specify an expected-votes value of zero (0). Likewise, it
prevents you from setting expected votes to any value less than
the currently available votes or to any value large enough to
cause the cluster to lose quorum. Prudence dictates that you
adjust expected votes by one vote at a time.
DESCRIPTION
The clu_quorum utility configures or deletes a quorum disk, and adjusts
quorum disk votes, member node votes, and expected votes. You must have
root privileges and be running on a cluster member to issue the clu_quorum
command. You cannot issue the clu_quorum command in a cluster while a
clu_add_member or clu_delete_member operation is in progress.
The clu_quorum command writes information about its progress to the file
/cluster/admin/clu_quorum.log.
Displaying Quorum Information
When specified without a target flag (or with the -f and/or -v flag), the
clu_quorum command displays information about the current quorum disk,
member node vote, and expected vote configuration of the cluster. This
information includes:
· Cluster common quorum data. This includes the device name of any
configured quorum disk, plus quorum information from the clusterwide
/etc/sysconfigtab.cluster file (clusterwide expected votes).
When a member is booted or rebooted into a cluster, a check script
compares the values of these attributes in its /etc/sysconfigtab file
against those in the clusterwide /etc/sysconfigtab.cluster file. If
the values differ, the check script copies the values in
/etc/sysconfigtab.cluster to the member's /etc/sysconfigtab and
displays a message. When the boot completes, you should run the
clu_quorum command and examine the running and file values of the
expected votes for that member. If there are discrepancies between the
running and file values, you should reboot the member to resolve them.
· Member-specific quorum data from each member's running kernel and
/etc/sysconfigtab file, plus an indication of whether the member is UP
or DOWN. By default, no quorum data is returned for a member with DOWN
status. However, as long as the DOWN member's boot partition is
accessible to the member running the clu_quorum command, you can use
the -f flag to display the DOWN member's file quorum data values.
When examining the output from the clu_quorum command, bear in mind
the following:
-- In a healthy cluster, the running and file values of the
attributes should be identical. If they are not (as could be the
case if you added a new member while a member is down), you
should issue the appropriate clu_quorum commands to fix the
discrepancy.
-- With the exception of each member's individual node votes value,
all cluster members should have the same value for each
attribute. If this is not true, you should issue the appropriate
clu_quorum commands to fix the discrepancy.
-- Expected votes is a dynamically calculated value that is based on
a number of factors (discussed in the TruCluster Server Cluster
Administration manual). Its value determines the value of quorum
votes. Expected votes should equal the sum of all member node
votes, including DOWN members, plus any quorum disk vote when a
quorum disk is configured. If this is not true, you should issue
the appropriate clu_quorum commands from a single cluster member
to adjust expected votes.
-- Current votes should equal the sum of the votes of all UP
members, plus the quorum disk vote if a quorum disk is configured
and on-line. If the value of current votes varies across cluster
members, it is possible that one or more members may no longer
have a direct connection to the quorum disk (for example, its I/O
adapter has failed). See the TruCluster Server Cluster
Administration manual for a discussion of cluster partitions and
methods for diagnosing them.
-- Quorum votes is a dynamically calculated value that indicates how
many votes must be present in the cluster for cluster members to
be allowed to participate in the cluster and perform productive
work. See the TruCluster Server Cluster Administration manual for
a discussion of quorum and quorum loss.
When you specify the -v option, the clu_quorum command displays the boot-
time values of expected votes, node votes, and quorum disk information for
each UP member. Use this information in conjunction with the data in the
/cluster/admin/clu_quorum.log file to determine what quorum modifications
have been made in the cluster since the cluster was booted.
Configuring and Managing a Quorum Disk
A quorum disk with a vote allows a two-member cluster to survive the
failure of a single member and can be useful in increasing availability in
other cluster configurations with an even number of members.
A quorum disk is typically assigned one vote. (However, it may be useful to
configure a quorum disk with zero votes in certain configurations so that
it can take over the vote of a member that is being shut down temporarily.)
Note that assigning a vote to a quorum disk in a one-member cluster
introduces a second point of failure. The failure of the disk will cause
the cluster to lose quorum and stall.
The following restrictions apply to the use of a quorum disk:
· A cluster can have only one quorum disk.
· The quorum disk should be on a shared bus to which all cluster members
are directly connected. If it is not, members that do not have a
direct connection to the quorum disk may lose quorum before members
that do have a direct connection to it.
· The quorum disk must not contain any data. The clu_quorum command will
overwrite existing data when initializing the quorum disk. The
integrity of data (or file system metadata) subsequently placed on the
quorum disk from a running cluster is not guaranteed across member
failures.
· The disks holding the clusterwide root (/) and member boot partition
cannot be used as a quorum disk.
· The quorum disk can be quite small (for example, as a logical disk
behind a hierarchical storage controller). The cluster subsystems use
only 1 MB of the disk.
When you specify the -d flag, the clu_quorum command adjusts the file and
running values of qdisk major, qdisk minor, qdisk votes, and expected votes
on each cluster member.
If you attempt to add a quorum disk and clu_quorum determines that the
specified disk is already in use, the command fails with a message such as:
*** Error ***
Disk 'dskxx' has at least one partition that is in use.
The partition in use is open as an Advfs Domain.
*** Error ***
Cannot configure quorum disk.
If you attempt to adjust qdisk votes to a value that would cause the
cluster to lose quorum, the clu_quorum command fails with a message such
as:
*** Error ***
The requested quorum disk vote adjustment would result in an
expected votes value of 'x'. This value would cause all members of the
current cluster configuration to lose quorum.
*** Error ***
Cannot adjust quorum disk votes.
If you attempt to add a quorum disk and that vote, when added, would be
needed to sustain quorum, the clu_quorum command displays the following
message:
Adding the quorum disk could cause a temporary loss
of quorum until the disk becomes trusted.
Do you want to continue with this operation? [yes]:
You can usually respond "yes" to this question. It usually takes about
twenty seconds for the clu_quorum command to determine the trustworthiness
of the quorum disk. For the quorum disk to become trusted, the member
needs direct connectivity to it, must be able to read to and write from it,
and must either claim ownership of it or be a member of the same cluster as
a member that claims ownership.
If you attempt to adjust the votes of an existing quorum disk and the
member does not consider that disk to be trusted (as indicated by a zero
value in the qdisk_trusted attribute of the cnx subsystem), the clu_quorum
command displays the following message:
The quorum disk does not currently appear to be trusted.
Adjusting the votes on the quorum disk could cause quorum loss.
Do you want to continue with this operation? [no]:
If the quorum disk is not currently trusted, it is unlikely to become
trusted unless you do something that allows it to meet the requirements
listed above. You should probably answer "no" to this question and
investigate other ways of adding a vote to the cluster.
If you attempt to either add a quorum disk or adjust its vote to 1, and
there are nonvoting members in the cluster, the clu_quorum command displays
the following message:
There appear to be non-voting member(s) in this cluster. If a non-voting
cluster member is unable to access the quorum disk, it may lose quorum.
Do you want to continue with this operation? [yes]:
You can usually respond "yes" to this question.
Adjusting Member Votes
When you specify the -m flag, the clu_quorum command adjusts the running
and file values of node votes on the target member. It also adjusts the
running and file values of expected votes on each cluster member and in the
clusterwide /etc/sysconfigtab.cluster file. Also, it may adjust quorum
votes, if appropriate.
If you attempt to adjust node votes to a value that would cause the cluster
to lose quorum, the clu_quorum command fails with a message such as:
*** Error ***
The requested member vote adjustment would result in an
expected votes value of 'x'. This value would cause all members of the
current cluster configuration to lose quorum.
*** Error ***
Cannot adjust member votes.
Adjusting Expected Votes
When you specify the -e flag, the clu_quorum command adjusts the running
and file values of expected votes on each cluster member and in the clubase
stanza of the clusterwide /etc/sysconfigtab.cluster file.
If you attempt to raise expected votes to a value that would cause the
cluster to lose quorum, the clu_quorum command fails with a message such
as:
*** Error ***
The requested expected vote adjustment would result in an
expected votes value of 'x'. This value would cause all members of the
current cluster configuration to lose quorum.
*** Error ***
Cannot adjust expected votes.
If you attempt to lower expected votes to a value that could cause the
cluster to partition, the clu_quorum command fails with a message such as:
*** Error ***
The requested expected vote adjustment would result in an illegal
expected votes value of 'x'. This value is too low.
*** Error ***
Cannot adjust expected votes.
EXAMPLES
The following command displays the quorum disk and vote assignments of a
cluster with three members (one of which is down) and a quorum disk.
# clu_quorum
Cluster Quorum Data for: deli as of Fri Nov 5 08:28:48 EST 1999
Cluster Common Quorum Data
Quorum disk: dsk10h
File: /etc/sysconfigtab.cluster
Attribute File Value
expected votes 4
Member 1 Quorum Data
Host name: polishham.zk3.dec.com Status: UP
File: /cluster/members/member1/boot_partition/etc/sysconfigtab
Attribute Running Value File Value
current votes 3 N/A
quorum votes 3 N/A
expected votes 4 4
node votes 1 1
qdisk votes 1 1
qdisk major 19 19
qdisk minor 207 207
Member 3 Quorum Data
Host name: pepicelli.zk3.dec.com Status: UP
File: /cluster/members/member3/boot_partition/etc/sysconfigtab
Attribute Running Value File Value
current votes 3 N/A
quorum votes 3 N/A
expected votes 4 4
node votes 1 1
qdisk votes 1 1
qdisk major 19 19
qdisk minor 207 207
Member 2 Quorum Data
Host name: provalone.zk3.dec.com Status: DOWN
File: /cluster/members/member2/boot_partition/etc/sysconfigtab
Use of the -f flag in the following clu_quorum command forces the display
the quorum disk and vote assignments of the member of the cluster that is
down in the prevous example. Use of the -v command includes boot-time
quorum information for all UP members.
# clu_quorum -v -f
Cluster Quorum Data for: deli as of Fri Nov 5 08:29:44 EST 1999
Cluster Common Quorum Data
Quorum disk: dsk10h
File: /etc/sysconfigtab.cluster
Attribute File Value
expected votes 4
Member 1 Quorum Data
Host name: polishham.zk3.dec.com Status: UP
File: /cluster/members/member1/boot_partition/etc/sysconfigtab
Attribute Running Value File Value Booted Value
current votes 3 N/A N/A
quorum votes 3 N/A N/A
expected votes 4 4 4
node votes 1 1 1
qdisk votes 1 1 1
qdisk major 19 19 19
qdisk minor 207 207 207
Member 3 Quorum Data
Host name: pepicelli.zk3.dec.com Status: UP
File: /cluster/members/member3/boot_partition/etc/sysconfigtab
Attribute Running Value File Value Booted Value
current votes 3 N/A N/A
quorum votes 3 N/A N/A
expected votes 4 4 4
node votes 1 1 1
qdisk votes 1 1 1
qdisk major 19 19 19
qdisk minor 207 207 207
Member 2 Quorum Data
Host name: provalone.zk3.dec.com Status: DOWN
File: /cluster/members/member2/boot_partition/etc/sysconfigtab
Attribute File Value
current votes N/A
quorum votes N/A
expected votes 4
node votes 1
qdisk votes 1
qdisk major 19
qdisk minor 207
The following example adds a quorum disk with one vote to the cluster:
# clu_quorum -d add dsk10 1
Collecting quorum data for Member(s): 1 3 2
Initializing cnx partition on quorum disk : dsk10h
qdisk_major: reconfigured
qdisk_minor: reconfigured
qdisk_votes: reconfigured
qdisk_oper: reconfigured
Quorum disk votes successfully adjusted.
The following example removes the quorum disk:
# clu_quorum -d remove
Collecting quorum data for Member(s): 1 3 2
qdisk_major: reconfigured
qdisk_minor: reconfigured
qdisk_votes: reconfigured
qdisk_oper: reconfigured
Quorum disk successfully removed.
EXIT VALUES
The exit values for clu_quorum are:
0 Successful completion.
1 An error has occurred.
FILES
/usr/sbin/clu_quorum
Specifies the command path.
/cluster/admin/clu_quorum.log
Log file for clu_quorum.
/etc/sysconfigtab
Member-specific configuration database
/etc/sysconfigtab.cluster
Database containing kernel attributes that must be set
identically in each member's /etc/sysconfigtab file.
RELATED INFORMATION
TruCluster Server Cluster Administration
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