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514 IBM System Storage DS6000 Series: Copy Services with IBM System z
Concurrent Copy throughput
Your workload flow and your hardware configuration determines how these factors affect your
ability to use Concurrent Copy.
When planning for the production use of Concurrent Copy, you should also address:
When to schedule Concurrent Copy operations
Where to use Concurrent Copy
Number of simultaneous sessions (z/OS Global Mirror and Concurrent Copy) that you can
run
Let us look at these considerations in more detail.
When to schedule Concurrent Copy
Many factors influence when you can schedule Concurrent Copy operations. For example,
the structure of your overnight batch processing determines at what stages in the processing
you can use Concurrent Copy. Similarly, factors such as availability of tape drives could
restrict the intervals during which running a Concurrent Copy operation is feasible.
If other considerations are not a factor, you can use Concurrent Copy at times of lowest
activity, especially lowest update activity. It might, however, be beneficial to use Concurrent
Copy to back up data even during periods of higher I/O activity. In some cases, ensuring data
availability may be more important than preserving levels of application performance.
Where to use Concurrent Copy
You can use Concurrent Copy to back up any data that can be backed up using DFSMSdss
because DFSMSdss is the external interface to Concurrent Copy. The general-purpose
design of Concurrent Copy simplifies the use of Concurrent Copy, because it builds on
existing experience with DFSMSdss.
For example, IMS databases can be backed up using DFSMSdss. During the recovery
process, IMS database recovery control (DBRC) coordinates recovery of the DFSMSdss
dump and the application of updates from the IMS log. The same is available also for DB2.
Data sets that are consistently in use, such as DFSMShsm control data sets, databases, and
libraries, require specialized facilities to ensure that data set backups are nondisruptive and
preserve data set integrity.
Management class attributes let you choose how DFSMShsm and DFSMSdss should
process data sets that are in use during availability management. Point-in-time capabilities
using Concurrent Copy on the ESS allow you to:
Use DFSMSdss to create a point of consistency backup of CICS, IMS, or DB2 databases
without needing to quiesce them during the entire backup process.
Use DFSMSdss to create backups of data sets without requiring serialization during the
entire backup process. DFSMSdss serializes the data during the Concurrent Copy
initialization period (the time between the start of DFSMSdss and the issuing of the
ADR734I message).
Create and maintain multiple backup versions of DFSMShsm control data sets, while
increasing the availability of DFSMShsm functions, such as recall.
Use the backup-while-open capability for CICS VSAM data sets with DFSMSdss in batch
mode or with automated DFSMShsm, to provide backups with data integrity even when
the data sets are being updated. Data integrity is assured for VSAM KSDSs even when
CICS access results in control interval or control area splits, or data set obtaining another
extent.