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Oracle Solaris Cluster Software Installation Guide     Oracle Solaris Cluster 4.1
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Document Information

Preface

1.  Planning the Oracle Solaris Cluster Configuration

2.  Installing Software on Global-Cluster Nodes

3.  Establishing the Global Cluster

4.  Configuring Solaris Volume Manager Software

Configuring Solaris Volume Manager Software

How to Install Solaris Volume Manager

How to Create State Database Replicas

Creating Disk Sets in a Cluster

How to Create a Disk Set

Adding Drives to a Disk Set

How to Add Drives to a Disk Set

How to Repartition Drives in a Disk Set

How to Create an md.tab File

How to Activate Volumes

Configuring Dual-String Mediators

Requirements for Dual-String Mediators

How to Add Mediator Hosts

How to Check For and Fix Bad Mediator Data

5.  Creating a Cluster File System

6.  Creating Zone Clusters

7.  Uninstalling Software From the Cluster

Index

Configuring Dual-String Mediators

This section provides information and procedures to configure dual-string mediator hosts.

A single disk string consists of a disk enclosure, its physical drives, cables from the enclosure to the node or nodes, and the interface adapter cards. A dual-string disk set includes disks in two disk strings, and is attached to exactly two nodes. If a single disk string in a dual-string disk set fails such that exactly half the Solaris Volume Manager replicas remain available, the disk set will stop functioning. Dual-string mediators are therefore required for all Solaris Volume Manager dual-string disk sets. The use of mediators enables the Oracle Solaris Cluster software to ensure that the most current data is presented in the instance of a single-string failure in a dual-string configuration.

A dual-string mediator, or mediator host, is a cluster node that stores mediator data. Mediator data provides information about the location of other mediators and contains a commit count that is identical to the commit count that is stored in the database replicas. This commit count is used to confirm that the mediator data is in sync with the data in the database replicas.

The following table lists the tasks that you perform to configure dual-string mediator hosts. Complete the procedures in the order that is indicated.

Table 4-3 Task Map: Configuring Solaris Volume Manager Dual-String Mediators

Task
Instructions
Configure dual-string mediator hosts.
Check the status of mediator data and, if necessary, fix bad mediator data.

Requirements for Dual-String Mediators

The following rules apply to dual-string configurations that use mediators.

These rules do not require that the entire cluster consist of only two nodes. An N+1 cluster and many other topologies are permitted under these rules.

How to Add Mediator Hosts

Perform this procedure if your configuration requires dual-string mediators.

  1. If you will use a third mediator host for a dual-string disk set and that host does not already have disk sets configured, modify the /etc/group file and create a dummy disk set.
    1. Add the entry root to the sysadmingroup in the /etc/group file.
    2. Create a dummy disk set by using the metaset command.
      phys-schost-3# metaset -s dummy-diskset-name -a -h hostname
      -s dummy-diskset-net

      Specifies the dummy disk set name.

      -a

      Adds to the disk set.

      -h hostname

      Specifies the name of the node.

  2. Assume the root role on the node that currently masters the disk set to which you intend to add mediator hosts.
  3. Add each node with connectivity to the disk set as a mediator host for that disk set.
    phys-schost# metaset -s setname -a -m mediator-host-list
    -s setname

    Specifies the disk set name.

    -m mediator-host-list

    Specifies the name of the node to add as a mediator host for the disk set.

    See the mediator(7D) man page for details about mediator-specific options to the metaset command.

Example 4-6 Adding Mediator Hosts

The following example adds the nodes phys-schost-1 and phys-schost-2 as mediator hosts for the disk set dg-schost-1. If needed, repeat the command a third time for a third mediator host. All commands are run from the node that masters the disk set for which you are adding mediator hosts, in this case phys-schost-1.

phys-schost# metaset -s dg-schost-1 -a -m phys-schost-1
phys-schost# metaset -s dg-schost-1 -a -m phys-schost-2
phys-schost# metaset -s dg-schost-1 -a -m phys-schost-3

Next Steps

Check the status of mediator data. Go to How to Check For and Fix Bad Mediator Data.

How to Check For and Fix Bad Mediator Data

Perform this procedure to repair bad mediator data.

Before You Begin

Ensure that you have added mediator hosts as described in How to Add Mediator Hosts.

  1. Display the status of the mediator data.
    phys-schost# medstat -s setname
    -s setname

    Specifies the disk set name.

    See the medstat(1M) man page for more information.

  2. Check the Status field of the medstat output for each mediator host.
    • If the status is Ok, no error condition exists.
    • If the status is Bad, repair the affected mediator host.
  3. Assume the root role on the node that owns the affected disk set.
  4. Remove all mediator hosts with bad mediator data from all affected disk sets.
    phys-schost# metaset -s setname -d -m mediator-host-list
    -s setname

    Specifies the disk set name.

    -d

    Deletes from the disk set.

    -m mediator-host-list

    Specifies the name of the node to remove as a mediator host for the disk set.

  5. Restore each mediator host that you removed in Step 4.
    phys-schost# metaset -s setname -a -m mediator-host-list
    -a

    Adds to the disk set.

    -m mediator-host-list

    Specifies the name of the node to add as a mediator host for the disk set.

    See the mediator(7D) man page for details about mediator-specific options to the metaset command.

Next Steps

Determine from the following list the next task to perform that applies to your cluster configuration.