Cautions and restrictions for
Virtual Partition Manager
- Increased cache memory requirements
Install additional cache memory before partitioning cache. Adding cache memory after CLPRs have been created is difficult and can be problematic. For details, see Calculating cache capacity.
- Impact on host performance
Creating and changing cache logical partitions can significantly degrade host performance and should only be performed during the initial installation and setup of the storage system or during maintenance. If you must perform these changes on a production machine, use Performance Monitor to verify that the write pending rate and sidefile occupancy rate of the CLPR and CLPR0 satisfy the following formulas on all MP unit:
- For CLPR with decreased cache capacity
Write pending rate x cache capacity before operation / cache capacity after operation < 30%
Sidefile occupancy rate x cache capacity before operation / cache capacity after operation < sleep wait threshold x 50%
- For CLPR with increased cache capacity
Sidefile occupancy rate < sleep wait threshold x 50%
- For CLPR with decreased cache capacity
- When you move resources in CLPRs, make sure that the writing pending rates of the MP unit for each CLPR are less than 50 percent at both the source and the destination. The process for changing the CLPR settings will be suspended until the write pending rates of each MP unit become less than 50 percent.
- Duration of cache partition operations
Adding or changing CLPR definitions or configurations can take hours to complete. After a CLPR operation has been started, you cannot cancel or modify the process until the operation is complete.
- Interoperability restrictions for cache partitioning
Application
Behaviors
ShadowImage/ ShadowImage for Mainframe
You cannot use ShadowImage or ShadowImage for Mainframe Quick Restore functions that affect multiple CLPRs.
Volume Migration
You cannot use Volume Migration when it affects multiple CLPRs.
Universal Replicator
Universal Replicator data volumes and journal volumes can belong to different CLPRs. All journal volumes in the same journal must belong to the same CLPR. If not, an error occurs.