Mode Category Description Default MCU/RCU
Mode 474 = ON: For a suspended UR pair, a TC (Sync) pair
can be created with the same P-VOL/S-VOL so that UR initial
copy time can be reduced by using the dedicated script.
Mode 474 = OFF (default): For a suspended UR pair, a TC
(Sync) pair cannot be created with the same P-VOL/S-VOL.
For this, the dedicated script cannot be used.
If the P-VOL and S-VOL are both DP-VOLs, initial copy
performance might not improve with SOM 474 set to ON.
This is because with DP-VOLs, not all areas in a volume are
allocated for UR; therefore not all areas in the P-VOL are
copied to the S-VOL. With less than the full amount of data in
the P-VOL being copied, the initial copy completes in a
shorter time, which might not be improved with SOM 474.
Notes:
1. Set this SOM for both primary and secondary storage
systems.
2. When this SOM is set to ON:
- Execute all pair operations from CCI/BCM.
- Use a dedicated script.
- Initial copy operation is prioritized over update I/O.
Therefore, the processing speed of the update I/O slows
down.
3. If this SOM is set to ON, the processing speed of update
I/O slows down by about 15 μs per command, version
downgrade is disabled, and Take Over is not available.
4. If this SOM is not set to ON for both sides, the behavior
is as follows:
• OFF in primary and secondary storage systems:
Normal UR initial copy performance.
• ON in the primary storage system/OFF in the
secondary storage system: TC Sync pair creation
fails.
• OFF in the primary storage system/ON in the
secondary storage system: The update data is
copied to the S-VOL synchronously.
5. While this SOM is set to ON, make sure not to perform
microcode downgrade to an unsupported version.
6. While this SOM is set to ON, make sure not to perform
the Take Over function.
7. This SOM cannot be applied to a UR pair that is the
second mirror in a URxUR multi-target configuration,
URxUR cascade configuration, or 3DC multi-target or
cascading configuration of three UR sites. If applied, TC
pair creation is rejected with SSB=CBED output.
8. Before setting SOM 474 to ON, make sure that SOM
1091 is set to OFF. If SOM 1091 is set to ON, set it to
OFF first, and then set SOM 474 to ON.
506
Universal
Replicator
This SOM is used to enable Delta Resync with no host update
I/O by copying only differential JNL instead of copying all
data.
The UR Delta Resync configuration is required.
Mode 506 = ON:
OFF Both
System option modes 359
System Administrator Guide for VSP Gx00 models and VSP Fx00 models
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