EMC VMAX 100K, Product Manual

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Automatically on a target of an SRDF or TimeFinder relationship if the source is
either a 5876 device with an odd number of cylinders, or a 5977 source that has
GCM set.
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Manually using Base Controls interfaces. The EMC Solutions Enabler SRDF Family
CLI User Guide provides additional details.
SRDF device pairs
An SRDF device is a logical device paired with another logical device that resides in a
second array. The arrays are connected by SRDF links.
Encapsulated Data Domain devices used for ProtectPoint cannot be part of an SRDF
device pair.
Enginuity 5773 through 5876
On arrays running Enginuity 5773 through 5876, an SRDF device can be tagged for
use with RecoverPoint. For such devices, refresh operations are allowed only on the
R1 side.
R1 and R2 devices
R1 devices are the member of the device pair at the source (production) site. R1
devices are generally Read/Write accessible to the host.
R2 devices are the members of the device pair at the target (remote) site. During
normal operations, host I/O writes to the R1 device are mirrored over the SRDF links
to the R2 device. In general, data on R2 devices is not available to the host while the
SRDF relationship is active. In SRDF synchronous mode, an R2 device can be in Read
Only mode that allows a host to read from the R2.
In a typical open systems host environment:
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The production host has Read/Write access to the R1 device.
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A host connected to the R2 device has Read Only (Write Disabled) access to the
R2 device.
Figure 25 R1 and R2 devices
Active host path
Recovery path
Write Disabled
SRDF Links
Optional remote host
Production host
R1 data copies to R2
Open systems hosts
R2
Read
Only
R1
Read/
Write
Remote replication solutions
SRDF device pairs 117