Mode Category Description Default
MCU/R
CU
• A system disk with available space of more than 130
MB (185 cylinders when the track format is
3380/6586/NF80, and 154 cylinders when the track
format is 3390/6588) must exist. (Otherwise, audit
log is not stored even this option is ON).
• Turn this option on after preparing a normal system
disk that meets the condition in (2). If Define
Configuration & Install is performed, turn this option
on after formatting the system disk.
690 Universal
Replicator
This option 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).Note: 1. This mode can be set online.2. This mode
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.
OFF .
696 Open This mode 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)Note:1. Set this mode to ON
when you want to enable the QoS function.
OFF .
701 Universal
Volume
Manager
Issues the Read command at the logical unit discovery
operation using UVM.
Mode 701 = ON: The Read command is issued at the
logical unit discovery operation.
Mode 701 = OFF: The Read command is not issued at the
logical unit discovery operation.
Notes:
1. When the Open LDEV Guard attribute (VMA) is
defined on an external device, set the system option
to ON.
2. When this option is set to ON, it takes longer time to
complete the logical unit discovery. The amount of
time depends on external storages.
3. With this system option OFF, if searching for external
devices with VMA set, the VMA information cannot be
read.
4. When the mode is set to ON while the following
conditions are met, the external volume is blocked.
OFF .
System option modes
B-13
Hitachi Unified Storage VM Block Module Hardware User Guide
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