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%
  • 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.
  • (VSP G350, VSP G370, VSP G700, VSP G900, and VSP F350, VSP F370, VSP F700, VSP F900) When you perform the following CLPR operations successively, you must wait for the current CLPR operation to complete before starting the next one:
    • Creating a CLPR
    • Deleting a CLPR
    • Moving resources within a CLPR
    • Editing CLPR settings (changing cache capacities)

    As an exception, you can move resources in a CLPR while resources are being moved in another CLPR.

  • 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.

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