Chapter 5 Administering Quorum
This chapter provides the procedures for administering quorum
within Sun Cluster.
This is a list of the procedures in this chapter.
Most examples shown in this chapter are from a three-node cluster.
See the Sun Cluster Concepts Guide for Solaris OS document for
a conceptual overview of quorum and quorum devices.
Administering Quorum Overview
You can use the scconf(1M) command to perform all quorum administrative
procedures. In addition, you can accomplish some procedures by using the scsetup(1M)
interactive utility or the SunPlex Manager GUI. Whenever possible, quorum
procedures are described in this chapter using scsetup.
The SunPlex Manager online help describes how to perform quorum procedures
using the GUI.
If any quorum-related scconf command is interrupted
or fails, the quorum configuration information can become inconsistent in
the cluster configuration database. If this occurs, either rerun the command
or run scconf with the reset option
to reset the quorum configuration.
Note –
The scsetup command is an interactive interface
to the scconf command. When scsetup
runs, the command generates scconf commands. These generated
commands are shown in the examples at the end of the procedures.
There are two commands that can be used to view the quorum configuration: scstat -q option and scconf -p. Most of the verification
steps in this chapter use scconf, but you can substitute scstat -q if you find its output more useful.
Table 5–1 Task List: Administering Quorum
Dynamic Reconfiguration With Quorum Devices
There
are a few issues you must consider when completing dynamic reconfiguration
(DR) operations on quorum devices in a cluster.
-
All of the requirements, procedures, and restrictions that
are documented for the Solaris DR feature also apply to Sun Cluster DR support
(except for the operating environment quiescence operation). Therefore, review
the documentation for the Solaris DR feature before using
the DR feature with Sun Cluster software. You should review in particular
the issues that affect non-network IO devices during a DR detach operation.
-
Sun Cluster rejects DR remove-board operations that are performed
when an interface is present that is configured for a quorum device.
-
If the DR operation would pertain to an active device, Sun
Cluster rejects the operation and identifies the devices that would be affected
by the operation.
To remove a quorum device, you must complete the following steps, in
the order indicated.
Table 5–2 Task Map: Dynamic Reconfiguration with Quorum Devices
How to Add a Quorum Device
You can also accomplish this procedure by using the
SunPlex Manager GUI. See the SunPlex Manager online help for more information.
To complete this procedure, identify a disk drive by its device ID (DID),
which is shared by the nodes. Use the scdidadm command
to see the list of DID names. Refer to the scdidadm(1M) man page
for additional information.
See the scsetup(1M)
and scconf(1M)
man pages for information on the commands used in this procedure.
-
Become superuser on any node of the cluster.
-
Enter the scsetup utility.
The Main Menu is displayed.
-
To work with quorum devices, type 1 (Quorum).
The Quorum Menu is displayed.
-
To add a quorum device, type 1 (Add a quorum disk).
Follow the instructions and type the name of the device to be used as
the quorum device.
-
Verify that the quorum device has been added.
-
Repeat Step 3 through Step 5 for
each group of nodes that shares a storage enclosure.
Example—Adding a Quorum Device
The following example shows the scconf command generated
by scsetup when it adds a quorum device and a verification
step.
Become superuser on any cluster node.
[Execute the scsetup utility:]
# scsetup
Select Quorum>Add a quorum disk.
Answer the questions when prompted.
[Verify that the scconf command completed successfully:]
scconf -a -q globaldev=d20
Command completed successfully.
Quit the scsetup Quorum Menu and Main Menu.
[Verify the quorum device is removed:]
# scstat -q
-- Quorum Summary --
Quorum votes possible: 4
Quorum votes needed: 3
Quorum votes present: 4
-- Quorum Votes by Node --
Node Name Present Possible Status
--------- ------- -------- ------
Node votes: phys-schost-1 1 1 Online
Node votes: phys-schost-2 1 1 Online
-- Quorum Votes by Device --
Device Name Present Possible Status
----------- ------- -------- ------
Device votes: /dev/did/rdsk/d3s2 1 1 Online
Device votes: /dev/did/rdsk/d4s2 1 1 Online
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How to Remove a Quorum Device
You can also accomplish this procedure by using the
SunPlex Manager GUI. See the SunPlex Manager online help for more information.
When a quorum disk is removed, it no longer participates in the voting
to establish quorum. Note that all two-node clusters require that at least
one quorum device be configured. If this is the last quorum device on a cluster, scconf(1M)
will fail to remove the device from the configuration.
Note –
If the device you intend to remove is the last quorum device in
the cluster, see the procedure How to Remove the Last Quorum Device From a Cluster.
-
Become superuser on any node in the cluster.
-
Determine the quorum device to be removed.
# scconf -pv | grep Quorum
|
-
Execute the scsetup(1M)
utility.
The Main Menu is displayed.
-
To work with the quorum device, type 1 (Quorum).
-
To remove the quorum device, type 2 (Remove a quorum
disk).
Answer the questions displayed during the removal process.
-
Quit scsetup.
-
Verify that the quorum device is removed.
Example—Removing a Quorum Device
This example shows how to remove a quorum device from a cluster with
two or more quorum devices configured.
Become superuser on any node and place the node to be removed in maintenance state.
[Determine the quorum device to be removed:]
# scconf -pv | grep Quorum
[Execute the scsetup utility:]
# scsetup
Select Quorum>Remove a quorum disk.
Answer the questions when prompted.
[Verify that the scconf command completed successfully:]
scconf -r -q globaldev=d4
Command completed successfully.
Quit the scsetup Quorum Menu and Main Menu.
[Verify the quorum device is removed:]
# scstat -q
-- Quorum Summary --
Quorum votes possible: 3
Quorum votes needed: 2
Quorum votes present: 3
-- Quorum Votes by Node --
Node Name Present Possible Status
--------- ------- -------- ------
Node votes: phys-schost-1 1 1 Online
Node votes: phys-schost-2 1 1 Online
-- Quorum Votes by Device --
Device Name Present Possible Status
----------- ------- -------- ------
Device votes: /dev/did/rdsk/d3s2 1 1 Online
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How to Remove the Last Quorum Device From a Cluster
If the device you intend to remove is not
the last quorum device in the cluster, use the previous procedure, How to Remove a Quorum Device.
Note –
All two-node clusters require at least one configured quorum device.
If this is the last quorum device on a two-node cluster, the cluster must
be placed into install mode before scconf(1M) allows you to remove the device from
the configuration. This should only be done if a node is being removed from
the cluster.
-
Become superuser on any node in the cluster and place the node to be
removed in maintenance state.
See How to Put a Node Into Maintenance State.
-
Place the cluster in install mode.
# scconf -c -q installmode
|
-
Remove the quorum device using the scconf command.
The scsetup(1M)
cluster-administration menu options are not available while the cluster is
in install mode.
# scconf -r -q globaldev=device
|
-
Verify that the quorum device has been removed.
Example—Removing the Last Quorum Device
This example shows how to remove the last remaining quorum device in
a cluster configuration.
[Become superuser on any node.]
[Place the cluster in install mode:]
# scconf -c -q installmode
[Remove the quorum device:]
# scconf -r -q globaldev=d3
[Verify the quorum device has been removed:]
# scstat -q
-- Quorum Summary --
Quorum votes possible: 2
Quorum votes needed: 2
Quorum votes present: 2
-- Quorum Votes by Node --
Node Name Present Possible Status
--------- ------- -------- ------
Node votes: phys-schost-1 1 1 Online
Node votes: phys-schost-2 1 1 Online
-- Quorum Votes by Device --
Device Name Present Possible Status
----------- ------- -------- ------
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How to Replace a Quorum Device
-
Configure a new quorum device on the storage enclosure that currently
includes the disk to be replaced.
You need to first add a new quorum device to the configuration to take
the place of the old device. See How to Add a Quorum Device to add a new quorum
device to the cluster.
-
Remove the failed disk as a quorum device.
See How to Remove a Quorum Device to remove the old quorum device from the
configuration.
-
Replace the failed disk.
Refer to the hardware procedures for your disk enclosure in theSun Cluster Hardware Administration
Manual for Solaris OS .
How to Modify a Quorum Device Node List
You can use the scsetup(1M)
utility to add a node to or remove a node from the node list of an existing
quorum device. To modify a quorum device's node list, you must remove the
quorum device, modify the physical connections of nodes to the quorum device
you removed, then add the quorum device to the cluster configuration again.
When a quorum device is added, scconf(1M) automatically configures the node-to-disk
paths for all nodes attached to the disk.
-
Become superuser on any node of the cluster.
-
Determine the name of the quorum device you are modifying.
# scconf -p | grep Quorum
|
-
Enter the scsetup utility.
The Main Menu is displayed.
-
Type 1 (Quorum) to work with quorum devices.
The Quorum Menu is displayed.
-
Type 2 (Remove a quorum disk) to remove the quorum
device.
Follow the instructions. You will be asked the name of the disk to be
removed.
-
Add or delete the physical node connections to the quorum device.
-
Type 1 (Add a quorum disk) to add a quorum device.
Follow the instructions. You will be asked the name of the disk to be
used as the quorum device.
-
Verify that the quorum device has been added.
Example—Modifying a Quorum Device Node List
The following example shows how to use the scsetup
utility to add nodes to or delete nodes from a quorum device node list. In
this example, the quorum device name is d2, and the final result of the procedures
adds another node to the quorum device node list.
[Become superuser on any node in the cluster.]
[Determine the quorum device name:]
# scconf -p | grep Quorum
Quorum devices: d2
Quorum device name: d2
Quorum device votes: 1
Quorum device enabled: yes
Quorum device name: /dev/did/rdsk/d2s2
Quorum device hosts (enabled): phys-schost-1 phys-schost-2
Quorum device hosts (disabled):
[Execute the utility:]
# scsetup
Type 1 (Quorum).
Type 2 (Remove a quorum disk).
Answer the questions when prompted.
You Will Need: Example:
quorum device name d2
[Verify that the scconf command completed successfully:]
scconf -r -q globaldev=d2
Command completed successfully.
Type 1 (Quorum).
Type 1 (Add a quorum disk).
Answer the questions when prompted.
You Will Need: Example:
quorum device name d2
[Verify that the scconf command completed successfully:]
scconf -a -q globaldev=d2
Command completed successfully.
Quit the scsetup utility.
[Verify that the correct nodes have paths to the quorum device.
In this example, note that phys-schost-3 has been added to the
enabled hosts list.]
# scconf -p | grep Quorum
Quorum devices: d2
Quorum device name: d2
Quorum device votes: 2
Quorum device enabled: yes
Quorum device name: /dev/did/rdsk/d2s2
Quorum device hosts (enabled): phys-schost-1 phys-schost-2
phys-schost-3
Quorum device hosts (disabled):
[Verify that the modified quorum device is online.]
# scstat -q
-- Quorum Votes by Device --
Device Name Present Possible Status
----------- ------- -------- ------
Device votes: /dev/did/rdsk/d2s2 1 1 Online
[Verify the quorum device is removed:]
# scstat -q
-- Quorum Summary --
Quorum votes possible: 4
Quorum votes needed: 3
Quorum votes present: 4
-- Quorum Votes by Node --
Node Name Present Possible Status
--------- ------- -------- ------
Node votes: phys-schost-1 1 1 Online
Node votes: phys-schost-2 1 1 Online
-- Quorum Votes by Device --
Device Name Present Possible Status
----------- ------- -------- ------
Device votes: /dev/did/rdsk/d3s2 1 1 Online
Device votes: /dev/did/rdsk/d4s2 1 1 Online
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How to Put a Quorum Device Into Maintenance State
Use the scconf(1M) command to put a quorum device
into maintenance state. The scsetup(1M) utility does not currently have this
capability. You can also accomplish this procedure by using the SunPlex Manager
GUI. See the SunPlex Manager online help for more information.
Put a quorum device into maintenance state when taking the quorum device
out of service for an extended period of time. This way, the disk device's
quorum vote count is set to zero and does not contribute to the quorum count
while the device is being serviced. While in maintenance state, the quorum
device's configuration information is preserved.
Note –
All two-node clusters require at least one configured quorum device.
If this is the last quorum device on a two-node cluster, scconf
will fail to put the device into maintenance state.
To put a cluster node into maintenance state, see How to Put a Node Into Maintenance State.
-
Become superuser on any node of the cluster.
-
Put the quorum device into the maintenance state.
# scconf -c -q globaldev=device,maintstate
|
-
-c
-
Specifies
the change form of the scconf command.
-
-q
-
Manages the
quorum options.
-
globaldev=device
-
Specifies the DID name of the disk device to change, for example, d4.
-
maintstate
-
Puts
the shared quorum device into maintenance state.
-
Verify that the quorum device is now in maintenance state.
The output for the device you placed in maintenance state should read
zero for the Quorum Device Votes.
# scconf -p | grep -i quorum
|
Example—Putting a Quorum Device Into Maintenance State
The following example shows how to put a quorum device into maintenance
state and how to verify the results.
# scconf -c -q globaldev=d20,maintstate
# scconf -p | grep -i quorum
Node quorum vote count: 1
Node quorum vote count: 1
Quorum devices: d20
Quorum device name: d20
Quorum device votes: 0
Quorum device enabled: no
Quorum device name: /dev/did/rdsk/d20s2
Quorum device hosts (enabled): phys-schost-2 phys-schost-3
Quorum device hosts (disabled):
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Where to Go From Here
To re-enable the quorum device, see How to Bring a Quorum Device Out of Maintenance State.
To put a node into maintenance state, see How to Put a Node Into Maintenance State.
How to Bring a Quorum Device Out of Maintenance State
After a quorum device has been in maintenance state, and is being brought
back online, use the following procedure to reset the quorum vote count to
the default. For cluster nodes, the default quorum count is one. For quorum
devices, the default quorum count is N-1, where N is the number of nodes with non-zero vote counts that have
ports to the quorum device.
You should run this procedure any time a quorum device has been put
into maintenance state and you are bringing it out of maintenance state.
Caution –
If you do not specify either the globaldev
or node options, the quorum count is reset for the entire
cluster.
To bring a cluster node as well as its associated quorum devices out
of maintenance state, see How to Bring a Node Out of Maintenance State.
-
Become superuser on any node of the cluster.
-
Reset the quorum count.
# scconf -c -q globaldev=device,reset
|
-
-c
-
Specifies
the change form of the scconf command.
-
-q
-
Manages the
quorum options.
-
globaldev=device
-
Specifies the DID name of the quorum device to reset, for
example, d4.
-
reset
-
The change
flag that resets quorum.
-
If you are resetting the quorum count because a node was in maintenance
state, reboot the node.
-
Verify the quorum vote count.
# scconf -p | grep -i quorum
|
Example—Resetting the Quorum Vote Count (Quorum Device)
The following example resets the quorum count for a quorum device back
to the default and verifies the result.
# scconf -c -q globaldev=d20,reset
# scconf -p | grep -i quorum
Node quorum vote count: 1
Node quorum vote count: 1
Quorum devices: d20
Quorum device name: d20
Quorum device votes: 1
Quorum device enabled: yes
Quorum device name: /dev/did/rdsk/d20s2
Quorum device hosts (enabled): phys-schost-2 phys-schost-3
Quorum device hosts (disabled):
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How to List the Quorum Configuration
You can also accomplish this
procedure by using the SunPlex Manager GUI. See the SunPlex Manager online
help for more information.
You do not need to be superuser to list the quorum configuration.
Note –
When you increase or decrease the number of node attachments to
a quorum device, the quorum vote count is not automatically recalculated.
You can reestablish the correct quorum vote if you remove all quorum devices
and then add them back into the configuration.
Use scconf(1M)
to list the quorum configuration.
# scconf -p | grep -i quorum
|
Example—Listing the Quorum Configuration
# scconf -p | grep “Quorum | vote”
Node quorum vote count: 1
Node quorum vote count: 1
Quorum devices: d20
Quorum device name: d20
Quorum device votes: 1
Quorum device enabled: yes
Quorum device name: /dev/did/rdsk/d20s2
Quorum device hosts (enabled): phys-schost-2 phys-schost-3
Quorum device hosts (disabled):
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