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Setting up shared storage

The following sections describe setting up SCSI and Fibre Channel devices that the cluster systems share. For VCS I/O fencing, the data disks must support SCSI-3 persistent reservations. You need to configure a coordinator disk group that supports SCSI-3 PR and verify that it works.

See Setting up I/O fencing.

See also the Veritas Cluster Server User's Guide for a description of I/O fencing.

Setting the SCSI identifier value

Typically, AIX SCSI adapters are set with a default identifier value of 7. Each device on a SCSI bus must have a unique SCSI identifier value. Therefore, when more than one system is connected to a SCSI bus, the SCSI identifier must be changed on one or more systems to a unique number, typically 5 or 6.

Perform the steps below if you are connecting to shared storage with shared SCSI devices.

1. Determine the SCSI adapters on each system:

   north # lsdev -C -c adapter | grep scsi

   scsi0 Available 11-08 Wide/Ultra-2 SCSI I/O Controller

   scsi1 Available 11-09 Wide/Ultra-2 SCSI I/O Controller

   south # lsdev -C -c adapter | grep scsi

   scsi0 Available 11-08 Wide/Ultra-2 SCSI I/O Controller

   scsi1 Available 11-09 Wide/Ultra-2 SCSI I/O Controller

2. Verify the SCSI ID of each adapter:

   north # lsattr -E -l scsi0 -a id

   id 7 Adapter card SCSI ID True

   north # lsattr -E -l scsi1 -a id

   id 7 Adapter card SCSI ID True

   south # lsattr -E -l scsi0 -a id

   id 7 Adapter card SCSI ID True

   south # lsattr -E -l scsi1 -a id

   id 7 Adapter card SCSI ID True

3. If necessary, change the SCSI identifier on each system so that it is unique:

   south # chdev -P -l scsi0 -a id=5

   scsi0 changed

   south # chdev -P -l scsi1 -a id=5

   scsi1 changed

4. Shut down all systems in the cluster.
5. Cable the shared storage as illustrated in the example below:

Click the thumbnail above to view full-sized image.

6. Restart each system. Once all systems have booted, use the lspv command to verify that each system can see all shared devices needed by the application.

Setting up Fibre Channel

 To set up fibre channel

1. Connect the Fibre Channel adapters and the shared storage devices to the same hub or switch. If a fibre switch is being used, be sure that zoning, if implemented, does not prevent all systems from seeing all shared devices required to run the critical application.
2. Reboot each system:

   ok shutdown -Fr

3. Once all systems have booted, use the lspv command to verify that each system can see all shared devices needed by the application.