Functional and Operational Characteristics
2–43
Hitachi VSP User and Reference Guide
855 ShadowImage,
ShadowImage
for Mainframe,
Volume
Migration
By switching the mode to ON/OFF when
ShadowImage is used with SOM 467 set to ON,
copy processing is continued or stopped as follows.
Mode 855 = ON:
When the amount of dirty data is within the range
from 58% to 63%, the next copy processing is
continued after the dirty data created in the
previous copy is cleared to prevent the amount of
dirty data from increasing (copy after destaging). If
the amount of dirty data exceeds 63%, the copy
processing is stopped.
Mode 855 = OFF (default):
The copy processing is stopped when the amount of
dirty data is over 60%.
Notes:
1. This mode is applied when all the following
conditions are met
ShadowImage is used with SOM 467 set to
ON.
Write pending rate of an MP blade that has
LDEV ownership of the copy target is high
Usage rate of a parity group to which the
copy target LDEV belongs is low.
ShadowImage copy progress is delayed.
2. This mode is available only when SOM 467 is set
to ON.
3. If the workload of the copy target parity group
is high, the copy processing may not be
improved even if this mode is set to ON
857 OPEN and
Mainframe
This mode enables or disables to limit the cache
allocation capacity per MPB to within 128 GB except
for cache residency.
Mode 857 = ON:
The cache allocation capacity is limited to within
128 GB.
Mode 857 = OFF (default):
The cache allocation capacity is not limited to within
128 GB.
Note:
This mode is used with VSP microcode version -04
(70-04-0x-00/00) and earlier. It is also applied
when downgrading the microprogram from V02
(70-02-02-00/00) or higher to a version earlier
than V02 (70-02-02-00/00) while over 128 GB is
allocated.
OFF -
Mode Category Description Default MCU/RCU
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