Hitachi VSP F400, System Administration Manual

Page: 361 / 414

Mode Category Description Default MCU/RCU
2. The micro-programs on both MCU and RCU must
support this SOM.
3. This SOM should be set when requested by the user.
4. Setting this SOM to ON is recommended when GAD is
installed, as the performance degradation is more likely
to occur due to active-active I/Os.
5. If the write-pending status remains at 60% or higher on
the RCU for a long time, it takes extra time for the
initial copy and resync copy to be completed due to the
slower copy operations.
6. Do not set this SOM if the primary or secondary system
is connected to USP V/VM with microcode earlier than
60-02-xx-xx/xx. If this SOM is applied and the write-
pending rate reaches 60%, pair suspend might occur.
7. As this SOM is enabled per storage system, in an
environment where TC and GAD are used, this SOM is
applied to both program products. When GAD is
installed in a storage system that already uses TC, TC
initial copy might take longer time.
690 Universal
Replicator This SOM is used to prevent Read JNL or JNL Restore when
the Write Pending rate on RCU exceeds 60% as follows:
•
When CLPR of JNL-Volume exceeds 60%, Read JNL is
prevented.
• When CLPR of Data (secondary)-Volume exceeds 60%,
JNL Restore is prevented.
Mode 690 = ON: Read JNL or JNL Restore is prevented
when the Write Pending rate on RCU exceeds 60%.
Mode 690 = OFF (default): Read JNL or JNL Restore is not
prevented when the Write Pending rate on RCU exceeds 60%
(the same as before).
Notes:
1. This SOM can be set online.
2. This SOM should be set per customer’s requests.
3. If the Write Pending status long keeps 60% or more on
RCU, it takes extra time for the initial copy to be
completed by making up for the prevented copy
operation.
4. If the Write Pending status long keeps 60% or more on
RCU, the pair status may become Suspend due to the
JNL-Vol being full.
5. When USP/NSC is used on the P-VOL side, this SOM
cannot be used. If this SOM is set to ON, SSB=8E08 on
the P-VOL side and SSB=C8D1 on the S-VOL side might
be output frequently.
OFF RCU
696 Open This SOM is available to enable or disable the QoS function.
Mode 696 = ON: QoS is enabled. (In accordance with the
Share value set to SM, I/Os are scheduled. The Share value
setting from RMLIB is accepted)
Mode 696 = OFF (default): QoS is disabled. (The Share
value set to SM is cleared. I/O scheduling is stopped. The
Share value setting from host is rejected.)
OFF -
System option modes 361
System Administrator Guide for VSP Gx00 models and VSP Fx00 models