IBM DS8882F Introduction And Planning Manual page 63

remote site, data at the local and intermediate sites is not affected.
Applications continue to run normally in either case.
With the incremental resynchronization function enabled on a
Metro/Global Mirror configuration, if the intermediate site is lost, the local
and remote sites can be connected, and only a subset of changed data is
copied between the volumes at the two sites. This process reduces the
amount of data needing to be copied from the local site to the remote site
and the time it takes to do the copy.
Multiple Target PPRC
Provides an enhancement to disaster recovery solutions by allowing data
to be mirrored from a single primary site to two secondary sites
simultaneously. The function builds on and extends Metro Mirror and
Global Mirror capabilities. Various interfaces and operating systems
support the function. Disaster recovery scenarios depend on support from
controlling software such as Geographically Dispersed Parallel Sysplex
(GDPS) and IBM Copy Services Manager.
z/OS Global Mirror
If workload peaks, which might temporarily overload the bandwidth of the
Global Mirror configuration, the enhanced z/OS Global Mirror function
initiates a Global Mirror suspension that preserves primary site application
performance. If you are installing new high-performance z/OS Global
Mirror primary storage subsystems, this function provides improved
capacity and application performance during heavy write activity. This
enhancement can also allow Global Mirror to be configured to tolerate
longer periods of communication loss with the primary storage
subsystems. This enables the Global Mirror to stay active despite transient
channel path recovery events. In addition, this enhancement can provide
fail-safe protection against application system impact that is related to
unexpected data mover system events.
The z/OS Global Mirror function is an optional function.
z/OS Metro/Global Mirror Incremental Resync
z/OS Metro/Global Mirror Incremental Resync is an enhancement for
z/OS Metro/Global Mirror. z/OS Metro/Global Mirror Incremental Resync
can eliminate the need for a full copy after a HyperSwap
3-site z/OS Metro/Global Mirror configurations. The storage system
supports z/OS Metro/Global Mirror that is a 3-site mirroring solution that
uses IBM System Storage Metro Mirror and z/OS Global Mirror (XRC).
The z/OS Metro/Global Mirror Incremental Resync capability is intended
to enhance this solution by enabling resynchronization of data between
sites by using only the changed data from the Metro Mirror target to the
z/OS Global Mirror target after a HyperSwap operation.
If an unplanned failover occurs, you can use the z/OS Soft Fence function
to prevent any system from accessing data from an old primary PPRC site.
For more information, see the GDPS/PPRC Installation and Customization
Guide, or the GDPS/PPRC HyperSwap Manager Installation and Customization
Guide.
z/OS Global Mirror Multiple Reader (enhanced readers)
z/OS Global Mirror Multiple Reader provides multiple Storage Device
Manager readers that allow improved throughput for remote mirroring
configurations in IBM Z environments. z/OS Global Mirror Multiple
Reader helps maintain constant data consistency between mirrored sites
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situation in
Chapter 3. Data management features
53