Sun Cluster System Administration Guide for Solaris OS

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

Task 

For Instructions, Go To... 

Add a quorum device to a cluster 

    - Use scsetup(1M)

How to Add a Quorum Device

Remove a quorum device from a cluster 

    - Use scsetup (to generate scconf)

How to Remove a Quorum Device

Remove the last quorum device from a cluster 

    - Use scsetup (to generate scconf)

How to Remove the Last Quorum Device From a Cluster

Replace a quorum device in a cluster 

    - Use the add and remove procedures 

How to Replace a Quorum Device

Put a quorum device into maintenance state 

(While in maintenance state, the quorum device does not participate in voting to establish the quorum.) 

    - Use scsetup (to generate scconf)

How to Put a Quorum Device Into Maintenance State

Reset the quorum configuration to its default state 

    - Use scsetup (to generate scconf)

How to Bring a Quorum Device Out of Maintenance State

List the quorum devices and vote counts 

    - Use scconf(1M)

How to List the Quorum Configuration

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.

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

Task 

For Instructions, Go To... 

1. Enable a new quorum device to replace the one being removed. 

How to Add a Quorum Device

2. Disable the quorum device to be removed. 

How to Remove a Quorum Device

3. Perform the DR remove operation on the device being removed. 

Sun Enterprise 10000 DR Configuration Guide and the Sun Enterprise 10000 Dynamic Reconfiguration Reference Manual (from theSolaris 8 on Sun Hardware and Solaris 9 on Sun Hardware collections.)

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.

  1. Become superuser on any node of the cluster.

  2. Enter the scsetup utility.


    # scsetup
    

    The Main Menu is displayed.

  3. To work with quorum devices, type 1 (Quorum).

    The Quorum Menu is displayed.

  4. 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.

  5. Verify that the quorum device has been added.


    # scstat -q
    

  6. 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

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.


  1. Become superuser on any node in the cluster.

  2. Determine the quorum device to be removed.


    # scconf -pv | grep Quorum
    

  3. Execute the scsetup(1M) utility.


    # scsetup
    

    The Main Menu is displayed.

  4. To work with the quorum device, type 1 (Quorum).

  5. To remove the quorum device, type 2 (Remove a quorum disk).

    Answer the questions displayed during the removal process.

  6. Quit scsetup.

  7. Verify that the quorum device is removed.


    # scstat -q
    

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

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.


  1. 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.

  2. Place the cluster in install mode.


    # scconf -c -q installmode
    

  3. 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
    

  4. Verify that the quorum device has been removed.


    # scstat -q
    

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
                    -----------         ------- -------- ------

How to Replace a Quorum Device

  1. 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.

  2. Remove the failed disk as a quorum device.

    See How to Remove a Quorum Device to remove the old quorum device from the configuration.

  3. 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.

  1. Become superuser on any node of the cluster.

  2. Determine the name of the quorum device you are modifying.


    # scconf -p | grep Quorum
    

  3. Enter the scsetup utility.


    # scsetup
    

    The Main Menu is displayed.

  4. Type 1 (Quorum) to work with quorum devices.

    The Quorum Menu is displayed.

  5. 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.

  6. Add or delete the physical node connections to the quorum device.

  7. 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.

  8. Verify that the quorum device has been added.


    # scstat -q
    

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

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.

  1. Become superuser on any node of the cluster.

  2. 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.

  3. 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): 

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 – 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.

  1. Become superuser on any node of the cluster.

  2. 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.

  3. If you are resetting the quorum count because a node was in maintenance state, reboot the node.

  4. 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): 

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):