LPAR Pre-Flight Check
The decision to share processing resources can also affect the final LPAR design. In an LPAR environment, you have the option to move CPU, interactive and memory among the various partitions.
The LPAR planning worksheets dont take into account the benefits of dynamic LPAR, which allow you to share or move resources from one partition to another and recognize the configuration change without an IPL. Dynamic LPAR, introduced with OS/400 V5R1, offers the potential to reduce overall hardware cost by using processing resources more efficiently. You may find that you have a processing environment that can easily leverage the dynamic movement of processing resources. For example, if you intend to create partitions that support specific geographic regions where its easy to anticipate resource needs, it will be easy to determine acceptable processing resources. If your resource sharing isnt as cut and dried as the previous example, you may want to err on the side of generosity.
Choosing to use dynamic LPAR requires some additional planning and configuration. During the configuration of each partition, youll be asked to allocate a minimum and maximum acceptable amount for CPU, interactive CPW and memory. Dynamic LPAR allows you to dynamically modify processing resource allocations to any value within the allocated range without IPLing the partition. Changes can be made in one of three ways: manually changing resource allocation, scheduling resource change or using third-party vendor tools.
Finally, shared IOPs configured within LPAR allow certain hardware to be shared among partitions. Tape or CD drives are often shared. If you dont intend to share equipment, then you must purchase necessary equipment for each partition.
Going back to the new 810 that you intend to order. Youve decided to use a skinny primary partition and two V5R2 secondary partitions. Because you plan to share processing resources and backup devices, you think a mid-level 810 will meet your needs. The system will include two towers to provide sufficient space for all of the required hardware features. Figure 1 shows a sample of a similar configuration designed using the LVT.
LPAR Software Considerations
In general, when operating in any release prior to V5R1 or using older hardware, all internal resource configurations are static. Configuration changes to CPU, memory, interactive and bus ownership require an IPL before the partition(s) recognize the resource change. On the other hand, dynamic LPAR features include dynamic movement of CPU, interactive CPW and memory among partitions, dynamic change of Virtual Ethernet LAN and HSL OptiConnect, and guest partitions used to host Linux.
The allowable level of OS/400 for secondary partitions is directly associated with the OS/400 level installed on the primary partition. For V5R1 and V5R2, the OS level of the secondary partitions can be the same as or plus/minus two releases of the primary partition beginning with V4R4.
The limitation is at V5R1 and V5R2 on the primary partitions. A V5R1 primary partition can support V5R2 on the secondary partitions (V4R4 and V4R5 are no longer supported). A V5R2 primary on the newer i800 and i810 POWER4 machines can only support V5R2 on the secondary partitions, which have the LPAR functionality of the primary OS/400 level installed.
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