Administering Quorum

This chapter provides the procedures for administering quorum within Sun Cluster.

This is a list of the procedures in this chapter.

• How to Add a Quorum Device

• How to Remove a Quorum Device

• How to Remove the Last Quorum Device From a Cluster

• How to Replace a Quorum Device

• How to Put a Quorum Device Into Maintenance State

• How to Bring a Quorum Device Out of Maintenance State

• How to List the Quorum Configuration

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.

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