Mode Category Description Default
MCU/R
CU
VOL. For this, the dedicated script cannot be used.Note:1.
Set this mode for both MCU and RCU.2. When the mode is
set to ON; - Execute all of 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 by about 15?s per
command. 3. If this mode is set to ON, the processing
speed of update I/O slows down by about 15?s per
command, version downgrade is disabled, and Take Over
is not available.
4. If the mode is not set to ON for both or either sides,
the behavior is as follows.
- Without setting on both sides: Normal UR initial copy
performance.- With setting on MCU/without setting on
RCU: TC Sync pair creation fails.- Without setting on MCU/
with setting on RCU: The update data for P-VOL is copied
to the S-VOL in synchronous manner.- While the mode is
set to ON, micro-program downgrade is disabled.- While
the mode is set to ON, Take Over function is disabled.-
The mode cannot be applied to a UR pair that is the 2nd
mirror in URxUR multi-target configuration or URxUR
cascade configuration. If applied, TC pair creation is
rejected with SSB=CBEE output.
491 ShadowImage Mode 491 is used to improve the performance of
ShadowImage and ShadowImage FCv1.
Mode 491 = ON: The option (Reserve05) of
ShadowImage/ ShadowImage for z/OS is available. If the
option is set to ON, the copy of ShadowImage/
ShadowImage for z/OS/ ShadowImage FCv1 will be
performed from 64 processes to 128 processes so that the
performance will be improved.
Mode 491 = OFF (default): The option (Reserve05) of
ShadowImage/ ShadowImage for z/OS is unavailable. The
copy of ShadowImage/ ShadowImage for z/OS/
ShadowImage FCv1 is performed with 64 processes.
Note:
• Apply mode 491 when the performance of
ShadowImage / ShadowImage FCv1 is important.
• Do not apply the mode when the host I/O
performance is important.
• The mode will be noneffective if 3 or more pairs of
BEDs are not mounted.
• The mode is noneffective for the NSC model.
• Set mode 467 to OFF when using mode 491, since the
performance may not improve.
OFF -
725 This option
determines an
action when
Not Ready is
returned from
OFF -
System option modes
B-7
Hitachi Unified Storage VM Block Module Hardware User Guide
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