Mode Category Description Default MCU/RCU
Note:
The mode status will not be changed by the microcode
exchange.
454 Virtual Partition
Manager
CLPR (Function of Virtual Partition Manager) partitions the
cache memory in the disk subsystem into multiple virtual
cache and assigns the partitioned virtual cache for each
use. If a large amount of cache is required for a specific
use, it can minimize the impact on other uses. The CLPR
function works as follows depending on whether SOM 454
is set to ON or OFF.
Mode 454 = OFF (default):
The amount of the entire destage processing is periodically
determined by using the highest workload of all CLPRs
(*a). (The larger the workload is, the larger the amount of
the entire destage processing becomes.)
*a: (Write Pending capacity of CLPR#x) ÷ (Cache capacity
of CLPR#x), x=0 to 31
CLPR whose value above is the highest of all CLPRs
Because the destage processing would be accelerated
depending on CLPR with high workload, when the workload
in a specific CLPR increases, the risk of host I/O halt would
be reduced.
Therefore, set Mode 454 to OFF in most cases.
Mode 454 = ON:
The amount of the entire destage processing is periodically
determined by using the workload of the entire system
(*b). (The larger the workload is, the larger the amount of
the entire destage processing becomes.)
*b: (Write Pending capacity of the entire system) ÷ (Cache
capacity of the entire system)
Because the destage processing would not be accelerated
even if CLPR has high workload, when the workload in a
specific CLPR increases, the risk of host I/O halt would be
increased. Therefore, it is limited to set Mode 454 to ON
only when a CLPR has constant high workload and it gives
priority to I/O
OFF
457 Universal Volume
Manager
This SOM has two purposes:
Mode 457 = ON:
1. It activates high speed LDEV Format for External
Volumes
The high speed LDEV format for external volumes is
available by setting system option mode 457 to ON.
When SOM 457 is ON, if you select an external
volume group and perform an LDEV format, any write
processing on the external logical units will be
skipped. However, if the emulation type of the
external LDEV is a mainframe system, the write
OFF MCU/RCU
System option modes 141
Hitachi Virtual Storage Platform G1000, G1500, and Virtual Storage Platform F1500 Hardware Guide
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