500 Implementing the IBM Storwize V5000
5. Click Close and the command panel returns to the Consistency Group window. The
reverse consistency group now shows as a 100% copied and all volumes in the original
FlashTestGroup were restored, as shown in Figure 10-72.
Figure 10-72 Consistency Group restored
10.2 Remote Copy
In this section, we describe how the Remote Copy function works in IBM Storwize V5000. We
also provide the implementation steps for Remote Copy configuration and management by
using the GUI.
Remote Copy consists of three methods for copying: Metro Mirror, Global Mirror, and Global
Mirror with Change Volumes. Metro Mirror is designed for metropolitan distances with a
synchronous copy requirement. Global Mirror is designed for longer distances without
requiring the hosts to wait for the full round-trip delay of the long-distance link through
asynchronous methodology. Global Mirror with Change Volumes is an added piece of
functionality for Global Mirror that is designed to attain consistency on lower-quality network
links.
Metro Mirror and Global Mirror are IBM branded terms for the functions Synchronous Remote
Copy and Asynchronous Remote Copy. Throughout this book, the term “Remote Copy” is
used to refer to both functions where the text applies to each term equally.
10.2.1 Remote Copy concepts
Remote Copy concepts are described in this section.
Partnership
When a partnership is created, we connect two separate IBM Storwize V5000 systems or an
IBM SAN Volume Controller, Storwize V3700, or Storwize V7000, and an IBM Storwize
V5000. After the partnership creation is configured on both systems, further communication
between the node canisters in each of the storage systems is established and maintained by
the SAN. All inter-cluster communication goes through the Fibre Channel network.
Important: The IBM Storwize V5000 automatically appends the -restore option to the
command.
Chapter 10. Copy services 501
The partnership must be defined on both IBM Storwize V5000 or on the IBM Storwize V5000
and the other IBM SAN Volume Controller, Storwize V3700, or Storwize V7000 storage
system to make the partnership fully functional.
Introduction to layers
IBM Storwize V5000 implements the concept of layers. Layers determine how the IBM
Storwize portfolio interacts with the IBM SAN Volume Controller. Currently, there are two
layers: replication and storage.
The replication layer is used when you want to use the IBM Storwize V5000 with one or more
IBM SAN Volume Controllers as a Remote Copy partner. The storage layer is the default
mode of operation for the IBM Storwize V5000, and is used when you want to use the IBM
Storwize V5000 to present storage to an IBM SAN Volume Controller.
The layer for the IBM Storwize V5000 can be switched by running svctask chsystem -layer
replication. Generally, switch the layer while your IBM Storwize V5000 system is not in
production. This situation prevents potential disruptions because layer changes are not
I/O-tolerant.
Figure 10-73 shows the effect of layers on IBM SAN Volume Controller and IBM Storwize
V5000 partnerships.
Figure 10-73 IBM Storwize V5000 virtualization layers
The replication layer allows an IBM Storwize V5000 system to be a Remote Copy partner with
an IBM SAN Volume Controller. The storage layer allows an IBM Storwize V5000 system to
function as back-end storage for an IBM SAN Volume Controller. An IBM Storwize V5000
system cannot be in both layers at the same time.
Interconnection: Interconnects between IBM Storwize products were introduced in
Version 6.3.0. Because IBM Storwize V5000 supports only version 7.10 or higher, there is
no problem with support for this functionality. However, any other Storwize product must be
at a minimum level of 6.3.0 to connect to the IBM Storwize V5000 and the IBM Storwize
V5000 must set the replication layer by using the svctask chsystem -layer replication
limitations that are described next.

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