IBM DS6000 - Manual (Page 539)

Appendix A. Concurrent Copy 515
Concurrent Copy coexistence with z/OS Global Mirror
The DS6000 is not supported as a source for z/OS Global Mirror, and so there should be no
concerns with coexistence.
Simultaneous Concurrent Copy sessions
As said before, each Concurrent Copy session generates additional channel load and
increases utilization of the storage paths within the DS6000. If you are running multiple
simultaneous Concurrent Copy sessions, it you could generate contention for these
resources, resulting in greater than normal queuing and extended response times.
Number of data mover-allowed sessions
In addition to the server and storage resources needed for running multiple SDM sessions,
you must consider the following design maximums:
16 data mover sessions per device (combined total of Concurrent Copy and/or z/OS
Global Mirror)
64 data mover sessions per DS6000 logical subsystem (combined total of Concurrent
Copy and/or z/OS Global Mirror)
2048 data mover sessions per DS6000 (2 Address Groups times 16 LSSs times 64)
If you attempt to use more than 16 data mover sessions per device, or more than 2048 data
mover sessions per DS6000 at the same time, you receive an error message, and the copy
continues using the traditional DFSMSdss copy.
Sessions for aggregate group
If you relate Concurrent Copy processing to the ABACKUP command for an aggregate group
that includes numerous data sets that are on multiple devices and LSSs, a separate
Concurrent Copy session is created for each LSS that has volumes containing data defined
by the aggregate.
SMF information
The SDM writes a system management facility (SMF) type 42 subtype 4 record that contains
session statistics for each Concurrent Copy session when the session ends. Concurrent
Copy records contain the identifier CC. Among other things, you can use the information in
this record to determine the following statistics:
Session initialization time
Maximum size of host cached storage subsystem sidefiles
Number of intercepted writes
The SMF type 42 subtype 4 record is described in detail in z/OS DFSMS Advanced Copy
Services, SC35-0428.
Examples of Concurrent Copy invocation
This section illustrates some examples of how Concurrent Copy can be invoked for either:
Full volume dump
Logical data set dump
Logical data set copy
Full volume copy invoking FlashCopy
We also discuss the invocation of Concurrent Copy from an application program.