IBM Flex System V7000 Expansion Enclosure 4939H29 Manual Do Utilizador

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Draft Document for Review January 29, 2013 12:52 pm
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IBM Flex System V7000 Storage Node Introduction and Implementation Guide
9.3  Remote Copy
In this section, we describe how the Remote Copy function works in IBM Flex System V7000 
Storage Node. We also provide the implementation steps, using the GUI, for Remote Copy 
configuration and management.
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. With Version 6.4.1, Global Mirror with Change Volumes is an 
added piece of functionality for Global Mirror 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.
9.3.1  Remote Copy concepts
In the remote copy there are a number of different possible concepts that may be used when 
performing the desired functions to successfully reach the desired goal. In this session we 
discuss these different concepts and the reasons for and results of their use.
Partnership
When creating a partnership, connect an IBM Flex System V7000 Storage Node to either 
another IBM Flex System V7000 Storage Node, IBM Storwize V7000 systems or IBM SAN 
Volume Controller (SVC) systems which are in separate clusters. These clusters may be 
separated by distance, but distance is not a requirement. After the partnership creation has 
been configured on both systems, further communication between the node canisters in each 
of the storage systems is established and maintained by the SAN network. All inter-cluster 
communication goes over either a Fibre Channel network or over an FCoE network. 
Partnership must be defined on both storage systems to make the partnership fully functional.
Though partnerships for remote copy are created between the IBM virtual storage systems, 
external storage system which are virtualized behind an IBM virtual storage system can be 
used as members of the storage pools which have source or target volumes as members of a 
remote mirrored pair. This does not mean that the external storage’s mirroring product is 
supported; but that the mdisk members can be  accessed as storage members of the IBM 
virtual storage system for use as virtual storage locations. This factor can impact the licensing 
of the remote copy service on the IBM virtual storage systems.
A parameter named layer has been added to the clustered system properties which can be 
changed from storage (default) to replication if you need to make a new relationship between 
the IBM Flex System V7000 Storage Node and an SVC system. You can only change this 
parameter using the CLI command chsystem. In SVC systems, this parameter is fixed to 
replication and cannot be changed.
Interconnection: Interconnects between an IBM Flex System V7000 Storage Node, an 
IBM Storwize V7000 or IBM SAN Volume Controller requires the use of Version 6.4.1. Both 
systems in the partnership must be at that level, and the IBM Flex System V7000 Storage 
Node must be set to the 
replication layer
 using the 
svctask chsystem -layer 
replication
. Usage limitations are described in “Introduction to layers”.