IBM manual 316 DS8000 Series Concepts and Architecture

impact when the actual switch uses P/DAS, although it is quicker and easier to allow for a brief service interruption and quickly switch to the new disk storage server. Because Metro Mirror provides data consistency at any time, the switch-over to the new disk server is simple and does not require further efforts to ensure data consistency at the receiving site. It is feasible to use the GUI-based approach because migration is usually a one time effort. Command-line interfaces such as TSO commands are an alternative and can be automated to some extent with REXX procedures.

When the source disk servers are not compatible with the DS8000 and the migration is based on a full volume, physical level, then there are options which depend on various circumstances which are different for each installation. When TDMF or FDRPAS is available and the customer is used to managing volume migration using these software tools, then it is a likely approach to use these tools for a larger scale migration as well. In other circumstances it might be feasible to include the migration as part of a total package when installing and implementing DS8000 disk storage servers. This is possible through IGS services which rely on FDRPAS, TDMF or Piper for z/OS. There is always DFSMSdss, which is still popular, but this approach usually requires an outage of the specific application systems.

Finally, the migration might be used as an opportunity to consolidate volumes at the same time. After a decision has been made about the new volume size, which is preferably a multiple of a 3390-1 or 1113 cylinders, it is required to logically move the data sets. One option is to rely on SMS-based allocation in a system-managed environment, combined with DFSMSdss and logical data set copies targeted from individual source volume sets or entire SMS storage groups. A variation here might be a combination of full volume physical copy for the very first volume copied to a larger target volume, followed by further logical-based copy operations with DFSMSdss after adjusting the VTOC and VTOC index information.

After the migration and storage consolidation you will be using a disk storage server technology that will serve you with promising performance and excellent scalability combined with rich functionality and high availability.

316DS8000 Series: Concepts and Architecture