IBM DS6000 Series ユーザーズマニュアル

DS6000 Series: Concepts and Architecture

Data migration is an important activity that needs to be planned well to ensure the success of 
DS6000 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 
to guarantee data integrity at any time.

In the course of a data migration you might consider consolidating the volume environment 
from which you are coming. 

A DS6800 can contain up to 32 logical control units (LCUs) at GA. This allows the DS6800 to 
simulate up to 32 times an IBM 3390-6 control unit image with 256 devices within each single 
control unit image. The number of supported volumes within a DS6800 is 32 x 256 devices 
which equals 8,192 logical volumes. This is twice as much as what an ESS 2105 can 
configure for a z/OS-based configuration. This suggests consolidation of multiple control units 
into a single DS6800 disk storage server. This requires careful planning, and depending on 
the configuration complexity, it might take weeks or months to complete the planning and 
perform the actual migration.

Another aspect of consolidation within a data migration effort might be to plan for larger 
volume sizes and consolidate or fold more than one source volume to a new and bigger 
target volume. Up to now most customers have relied on a standard sized volume, that being 
an IBM 3390-3 with 3,339 cylinders. With the affinity of volumes to RAID arrays and the 
underlying 8-packs, the increasing DDM size in the ESS 2105 made it impossible to utilize the 
full RAID array capacity of a RAID rank with 146 GB and even larger DDMs, when choosing 
3390-3 volumes. The full RAID array capacity could only be utilized when changing to bigger 
volume sizes to reduce the number of volumes per RAID array or LSS. This is not necessary 
any more with the DS6800 model due to its flexibility to configure its backend storage 
independently from DDM sizes. There is no affinity any longer between an LSS and physical