Planning for nonshared disk storage

These considerations include:

• Internal disks. The internal disks on each node in a cluster must provide sufficient space for:
  • AIX® software (approximately 500 MB)
  • PowerHA® SystemMirror® software (approximately 50 MB for a server node)
  • Executable modules of highly available applications
• Root volume group. The root volume group for each node must not reside on the shared SCSI bus.
• AIX Error Notification Facility. Use the AIX Error Notification Facility to monitor the disks and adapters on each node. You can enable the automatic error notification in PowerHA SystemMirror to monitor both shared and nonshared disks by entering smit sysmirror from the command line and selecting Problem Determination Tools > PowerHA SystemMirror Error Notification > Configure Automatic Error Notification > Add Error Notify Methods for Cluster Resources.
• Disk adapter use. Because shared disks require their own adapters, you cannot use the same adapter for both a shared and a nonshared disk. The internal disks on each node require one SCSI adapter apart from any other adapters within the cluster.
• Volume group use. Internal disks must be in a different volume group from the external shared disks.

The executable modules of the highly available applications should be on the internal disks and not on the shared external disks, for the following reasons:

• Licensing
• Application startup