Planning Volume 2, Control Workstation and Software Environment

Question 9: Defining your system images

After determining the quantity and the type of nodes you need, you can decide which system image you want installed on which nodes. The system image is the collection of SP software components that is stored at a node. You can have a different system image on every node, the same system image on every node, or any combination in between. As you make this decision, there are performance and system management implications to consider.

The most significant implication is that if all the node images are the same, the installation and backup or restore functions are simpler. As discussed in the disk storage question, whether you install your applications on each node or on one node greatly affects the amount of disk storage space required for each node. While local node copies of applications offer faster performance, they require separate upgrades and system backups.

If you decided to have system partitions, you need to decide how many partitions you want and which nodes go with which partition. To fully understand partitioning, read Chapter 7, Planning SP system partitions before you make any decisions about system partitions.

You can also have one or more alternate root volume groups defined on any of the nodes. This allows you to easily switch between multiple system images on the node. The node can assume any one of several different personalities. Remember that the alternate root volume groups on a node cannot share a disk. You must have at least one disk for each root volume group.

The AIX mksysb image (SPIMG) that comes with PSSP does not have the AIX trusted computing base option enabled. If you want to have the trusted computing base option enabled, you must create and use your own customized mksysb. Customization to enable that option can only be done during your installation phase before you create the mksysb. See the information about working with the AIX image in the book PSSP: Installation and Migration Guide.

Specifying more than one system image

Worksheets 11 and 12 help you lay out each system image that you want to define for the SP nodes. The control workstation is defined in the next section. Make a copy of both worksheets for each image or alternate image that you plan to have. Use Worksheet 11 for AIX and its options, IBM licensed programs, and other programs you choose to have in your system image. Use Worksheet 12 to select the optional components of PSSP that you choose to install. The ssp image is included for informational purposes. It contains all the base components of PSSP that are not optional.

IBM provides one or more minimal system images (SPIMG) with the PSSP installation media. It might or might not contain all the parts of AIX that you want installed on each node. For example, it does not contain AIX windows support. The Read This First document that you receive with PSSP will give you the latest information on the minimal image file sets. Make certain you use the listing for the PSSP level on your system.

When you come to the question about where you want to install the rootvg, you are deciding on which internal disk drive the SPIMG should be placed. You might be planning to install external disks, but IBM suggests that the SPIMG be placed on an internal drive.

To specify system images, the ABC Corporation filled out Worksheet 11, Table 18. To specify PSSP components, they filled out Worksheet 12, Table 19.

Table 18. ABC Corporation's system images

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|Table 19. File set list for PSSP 3.4