B.2.3 Using the Disk ID Driver

All new installations running Solstice DiskSuite require a Disk ID (DID) pseudo driver to make use of disk IDs. Disk IDs enable metadevices to locate data independent of the device name of the underlying disk. Configuration changes or hardware updates are no longer a problem because the data is located by Disk ID and not the device name.

To create a mapping between a disk ID and a disk path, you run the scdidadm(1M) command from node 0. The scdidadm(1M) command sets up three components:

• Disk ID (DID) - This is a "short-hand" number assigned to the physical disk, such as "1."

• DID Instance Number -This is the full path to the raw disk device, such as phys-hahost3:/dev/rdsk/c0t0d0.

• DID Full Name - This is the full path of the DID, such as /dev/did/rdsk/d1.

The Solstice HA 1.3 release supported two-node clusters only. In this two-node configuration, both nodes were required to be configured identically on identical platforms, so the major/minor device numbers used by the Solstice DiskSuite device driver were the same on both systems. In greater than two-node configurations, it is difficult to cause the minor numbers of the disks to be identical on all nodes within a cluster. The same disk might have different major/minor numbers on different nodes. The DID driver uses a generated DID device name to access a disk that might have different major/minor numbers on different nodes.

Although use of the DID driver is required for clusters using Solstice DiskSuite with more than two nodes, the requirement has been generalized to all new Solstice DiskSuite installations. This enables future conversion of two-node Solstice DiskSuite configurations to greater than two-node configurations.

If you are upgrading from HA 1.3 to Sun Cluster 2.2, you do not need to run the scdidadm(1M) command.