openSolaris 2008 - Multi-Owner Disk Set Concepts - Solaris Volume Manager Administration Guide

Multi-Owner Disk Set Concepts

The storage managed by Solaris Volume Manager for Sun Cluster is grouped into multi-owner disk sets. Multi-owner disk sets allow multiple nodes to share ownership of a disk set and to simultaneously write to the shared disks. An instance of an application such as Oracle Real Application Clusters runs on each node in the cluster, so multi-owner disk sets provide scalability. Since each instance of the application directly accesses the shared storage, multi-owner disk sets also enhance the performance of the application.

Note - Multi-owner disk set functionality is enabled only in a Sun Cluster environment. Nodes are the physical machines that are part of a Sun Cluster system.

Each multi-owner disk set is associated with a list of nodes. These nodes share ownership of the disk set. The following metaset -s disk-set command shows the output for a multi-owner disk set.

# metaset -s blue

Multi-owner Set name = blue, Set number = 1, Master = nodeone

Host                Owner          Member
  nodeone           multi-owner   Yes 
  nodetwo           multi-owner   Yes 

Drive    Dbase

d9       Yes  

d13      Yes

This output shows nodeone and nodetwo in the list of nodes that share ownership of the disk set. Additionally, nodeone is designated as the master node.

Each multi-owner disk set has a master node. After a disk set is created, the node that adds the first disk to the disk set becomes the master node of the disk set. The master node creates, deletes, and updates the state database replicas in the disk set.

Note - For more information on state database replicas, see Chapter 6, State Database (Overview).

Solaris Volume Manager for Sun Cluster can support disk sets with different, yet overlapping, node lists. Because each disk set has a master node, multiple masters can exist simultaneously on the same cluster.

The following output from the metaset command shows that nodeone becomes the master node when the first disk is added to the disk set.

nodeone# metaset -s red
Multi-owner Set name = red, Set number = 1, Master = 

Host                Owner          Member
  nodeone                           Yes 
  nodetwo                           Yes 
nodeone# metaset -s red -a /dev/did/dsk/d9
nodeone# metaset -s red

Multi-owner Set name = red, Set number = 1, Master = nodeone 

Host                Owner          Member
  nodeone           multi-owner     Yes 
  nodetwo           multi-owner     Yes 

Drive     Dbase

d9        Yes

Tasks Associated With Multi-Owner Disk Sets

Caution - Before configuring multi-owner disk sets, you must have the following software installed, in addition to the Solaris OS:

Sun Cluster initial cluster framework
Sun Cluster Support for Oracle Real Application Clusters software
Oracle Real Application Clusters software

For information on setting up Sun Cluster and Oracle Real Application Clusters software, see Sun Cluster Software Installation Guide for Solaris OS and Sun Cluster Data Service for Oracle Real Application Clusters Guide for Solaris OS.

Solaris Volume Manager for Sun Cluster generally uses the same set of Solaris Volume Manager commands to perform tasks associated with disk sets. Some command options unique to multi-owner disk sets have been added to the metaset command. For example, the task to create a multi-owner disk set requires the -M to the metaset command. The following output shows you how to create a multi-owner disk set using the metaset -s diskset-name -a -M -h hostname command.

# metaset -s red -a -M -h nodeone
# metaset
Multi-owner Set name = red, Set number = 1, Master = 

Host                Owner          Member
  nodeone                          Yes

In addition, some of the metaset command options, such as the commands to take and release disk sets, are not used with multi-owner disk sets. For more information, see the metaset(1M) man page.

Another example of how tasks differ in a Sun Cluster environment occurs when working with disks. Sun Cluster assigns each disk a unique device ID (DID) number. Rather than using the cntndn format to identify a disk, use the Sun Cluster DID path name, /dev/did/dsk/dN. The variable N is the device number assigned by Sun Cluster.

The following output shows you how to add a disk to a multi-owner disk set using the metaset -s diskset-name -a disk-name command and the Sun Cluster DID path name to identify the disk.

nodeone# metaset -s red
Multi-owner Set name = red
Multi-owner Set name = red, Set number = 1, Master = 

Host                Owner          Member
  nodeone                           Yes 
  nodetwo                           Yes 
nodeone# metaset -s red -a /dev/did/dsk/d13
nodeone# metaset -s red
Multi-owner Set name = red, Set number = 1, Master = nodeone

Host                Owner          Member
  nodeone            multi-owner   Yes

Drive Dbase

d13   Yes

For information on creating multi-owner disk sets for the Oracle Real Application Clusters, see Creating a Multi-Owner Disk Set in Solaris Volume Manager for Sun Cluster for the Oracle Real Application Clusters Database in Sun Cluster Data Service for Oracle Real Application Clusters Guide for Solaris OS.

For tasks that are associated with disk sets, see Chapter 19, Disk Sets (Tasks).