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72
DS8880 Introduction and Planning Guide
With backups that are outside of the production environment, you can use the
backups to restore your environment back to a specified point in time. You can
also extract and restore specific data from the backup or use the backup to
diagnose production issues.
You cannot delete a safeguarded source volume before the safeguarded backups
are deleted. The maximum size of a backup is 16 TB.
Copy Services Manager (available on the Hardware Management Console) is
required to facilitate the use and management of Safeguarded Copy functions.
Remote mirror and copy
The remote mirror and copy feature is a flexible data mirroring technology that
allows replication between a source volume and a target volume on one or two
disk storage systems. You can also issue remote mirror and copy operations to a
group of source volumes on one logical subsystem (LSS) and a group of target
volumes on another LSS. (An LSS is a logical grouping of up to 256 logical
volumes for which the volumes must have the same disk format, either count key
data or fixed block.)
Remote mirror and copy is an optional feature that provides data backup and
disaster recovery.
Note: You must use Fibre Channel host adapters with remote mirror and copy
functions. To see a current list of environments, configurations, networks, and
products that support remote mirror and copy functions, click Interoperability
Matrix at the following location IBM System Storage Interoperation Center (SSIC)
website (www.ibm.com/systems/support/storage/config/ssic).
The remote mirror and copy feature provides synchronous (Metro Mirror) and
asynchronous (Global Copy) data mirroring. The main difference is that the Global
Copy feature can operate at long distances, even continental distances, with
minimal impact on applications. Distance is limited only by the network and
channel extenders technology capabilities. The maximum supported distance for
Metro Mirror is 300 km.
With Metro Mirror, application write performance depends on the available
bandwidth. Global Copy enables better use of available bandwidth capacity to
allow you to include more of your data to be protected.
The enhancement to Global Copy is Global Mirror, which uses Global Copy and
the benefits of FlashCopy to form consistency groups. (A consistency group is a set
of volumes that contain consistent and current data to provide a true data backup
at a remote site.) Global Mirror uses a master storage system (along with optional
subordinate storage systems) to internally, without external automation software,
manage data consistency across volumes by using consistency groups.
Consistency groups can also be created by using the freeze and run functions of
Metro Mirror. The freeze and run functions, when used with external automation
software, provide data consistency for multiple Metro Mirror volume pairs.
The following sections describe the remote mirror and copy functions.
Synchronous mirroring (Metro Mirror)
Provides real-time mirroring of logical volumes (a source and a target)
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