IBM DS8000 manual Define migration objectives in z/OS environments, Consolidate storage subsystems

14.1 Define migration objectives in z/OS environments

Data migration is an important activity that needs to be planned well to ensure the success of the DS8000 implementation. Because today’s business environment does not allow you to interrupt data processing services, it is crucial to make the data migration onto the new storage servers as smooth as possible. The configuration changes and the actual data migration ought to be transparent to the users and applications, with no or only minimal impact on data availability. This requires you to plan for non-disruptive migration methods and also to guarantee data integrity at any time during the migration process.

14.1.1 Consolidate storage subsystems

In the course of a data migration you might consider consolidating volumes and reducing the number of storage servers.

FICON
			FICON
Storage subsystem
FICON			Storage server
	disk servers	Consolidate
Storage subsystem	Source
FICON
			Not drawn to scale
Storage server

Figure 14-1 Consolidation opportunities when migrating to DS8000

A DS8100 or DS8300 can initially contain up to 64 logical control units (LCUs), and this will later increase to 255 LCUs within a DS8000 storage server image. This allows the DS8100 or DS8300 to simulate up to 255 times an IBM 3390-6 control unit image with 256 devices within each single control unit image. 255 times 256 equals the maximum number of devices a storage server image can manage, which is 65,280 volumes. This suggests consolidation of multiple control units into a single DS8100 or DS8300 disk storage server.

On the other hand, you might consider having multiple physical footprints to disperse volumes for availability. Possible target configurations may conflict with recommendations from software platforms, where physical placement of specific data sets into separate physical hardware is recommended for availability. For example, the manual z/OS V1 R6.0 MVS Setting up a Sysplex, SA22-7625-09, states:

294DS8000 Series: Concepts and Architecture