User guide

System option modes B–11
Hitachi Unified Storage VM Block Module Hardware User Guide
491 ShadowImage Mode 491 is used for improving the performance of
ShadowImage / ShadowImage FCv1.
Mode ON: The option (Reserve05) of ShadowImage is
available. If the option is set to ON, the copy of
ShadowImage / ShadowImage FCv1 will be performed
from 64 processes to 128 processes so that the
performance will be improved.
Mode OFF (default): The option (Reserve05) of
ShadowImage is unavailable. The copy of
ShadowImage/ ShadowImage FCv1 is performed with 64
processes.
Note:
1. Make sure to apply mode 491 when the performance
of ShadowImage / ShadowImage FCv1 is considered to
be important.
2. Make sure not to apply the mode when the host I/O
performance is considered to be important.
3. The mode will be noneffective if 3 or more pairs of
DKAs are not mounted.
4. Make sure to set mode 467 to OFF when using mode
491, since the performance may not improve.
5. The mode is noneffective for the NSC model.
OFF .
561 ShadowImage,
Universal
Volume
Manager
Allows Quick Restore for external volumes with different
Cache Mode settings.
Mode 561 = ON: Quick Restore for external volumes with
different Cache Mode settings is prevented.
Mode 561 = OFF (default): Quick Restore for external
volumes with different Cache Mode settings is allowed.
OFF MCU/
RCU
589 Universal
Volume
Manager
Turning this option ON changes the frequency of
progress updates when disconnecting an external
volume. of disconnection is changed.
improvement in destaging to the pool by achieving
efficient HDD access.
Mode 589 = ON: For each external volume, progress is
updated only when the progress rate is 100%
Mode 589 = OFF (default): Progress is updated when the
progress rate exceeds the previous level.
Notes:
1. Set this option to ON when disconnecting an external
volume while the specific host IO operation is online
and its performance requirement is severe.
2. Whether the disconnecting status for each external
volume is progressed or not cannot be confirmed on
Storage Navigator (It indicates “-“ until just before
the completion and at the last it changes to 100%).
OFF .
Mode Category Description Default
MCU/
RCU