Conversion Procedures › Migrating to Dynamic Cache Management › Minimum Requirements - Quick or Phased Migration

Minimum Requirements - Quick or Phased Migration

Regardless of the conversion method chosen, Quick or Phased, some steps are common to both. These common steps form the minimum requirements that must be considered so that dynamic mode Virtual Volumes are properly allocated and can be mounted by any SVTS subsystem. The common items include the following:

• To run in dynamic mode, all SVTS subsystems sharing the same set of control files must be running at least r11.5 of CA Vtape. Multiple subsystems in a mixed mode environment (where some are dynamic and others are static) must run downward-compatible software. CA Vtape r11.5 prevents you from running incompatible modes. If all SVTS subsystems are running in static mode, a mix of CA Vtape r11 SP01 and CA Vtape r11.5 subsystems is allowed. Software levels lower than r11 SP01 are not compatible with CA Vtape r11.5 running with Dynamic Cache Management active.
• Use ISMF to create or review the DFSMS constructs intended for use by CA Vtape (data class, storage class, and storage group are all required). You should create and assign a unique set of constructs for use by CA Vtape in order to avoid confusion.

  A complete description and example of the data class and storage class definitions required for CA Vtape can be found in the section Setting up Dynamic Cache Management.

Important! The data class and storage class attribute definitions must allow the SVTS subsystem to allocate DFSMS managed linear data sets (LDS) that are single striped extended format, (multi-striped data sets will prevent CA Vtape from releasing unused DASD space) that can be allocated as multivolume and that support Space Constraint Relief.

• Check that the DFSMS automated class selection (ACS) rules will properly assign the appropriate DFSMS constructs to the dynamic cache LDSs.

  Note: Assigning available DASD volumes to the dynamic cache storage group to support the conversion of the first SVTS subsystem, rather than converting static cache DASD volumes, will eliminate any conversion impact on the subsystems that continue to run in static mode. These subsystems will continue to have the full static cache available to support their workload until DASD volumes are converted to support the conversion of the second SVTS subsystem to dynamic mode.

• Review the CA Vtape documentation and update the following attributes of the VTPARMS parmlib member of each subsystem sharing the same set of control files (BSDS and Global VCAT):
  • CacheDefaultDataClass='your cache LDS DataClas'
  • CacheDefaultStorageClass='your cache LDS StorClas'
  • CacheFreeSpaceThreshold=90
  • CachePrimary =200
  • CacheSecondary=200

  Note: If you have more than one CA Vtape subsystem and each has its own set of parmlib members, you must make changes in more than one parmlib member.

• Restart one of your SVTS subsystems. While you have not yet modified the cache management mode (CacheManagement=STATIC), you can still check that the DFSMS constructs you have chosen are properly assigned.

  Use the SVTS DISPLAY CACHE command to check the data and storage class values assigned by DFSMS. This command also displays DASD storage usage and gives you some sense of useable space within the storage class. Remember that class constructs specified in CA Vtape may be inadvertently overridden by the automated class selection (ACS) logic. Check to ensure that the construct values assigned by SVTS are assigned and not somehow overridden.