EMC CX700 Planning Manual page 83

Data Replication and Data Mobility Software
Before taking a snapshot, make sure that the secondary LUN is in a normal
condition and not updating. A snapshot of a secondary LUN when
MirrorView/A is updating the secondary will not give consistent data.
To provide for disaster recovery, the primary and secondary storage
systems should be geographically separated. MirrorView/A ensures
that data from the primary storage system replicates to the secondary.
The server (if any) connected to the secondary might sit idle until the
primary site fails. With SnapView at the secondary site, the server at
the secondary site can take snapshots of the mirror images and back
them up to other media. This provides point-in-time snapshots of
production data with little impact to production host performance.
You can create a snapshot of a mirrored LUN, but you cannot create a clone
(BCV) of a mirrored LUN.
Replication Over Long Distances
MirrorView/A uses FC-to-IP devices to provide replication over long
distances (hundreds to thousands of miles).
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What Is MirrorView/A?