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Chapter 6 RAID Group Management
6.2 Functions in the Action Area for RAID Group
ETERNUS Web GUI User’s Guide
Copyright 2013 FUJITSU LIMITED P2X0-1090-10ENZ0
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- Low
Perform rebuild, copyback, and redundant copy with a normal priority.
- Middle
Give the same priority as the host access to rebuild, copyback, and redundant copy.
- High
Give priority to rebuild, copyback, and redundant copy over host access.
• Disk Tuning Parameter Setting
Specify whether to enable or disable the following disk tuning parameters.
- Throttle
- Ordered Cut
The default value varies depending on the storage system model. When using the ETERNUS DX80
S2/DX90 S2 or the ETERNUS DX410 S2/DX440 S2, the default setting is "Disable". When using the
ETERNUS DX8100 S2/DX8700 S2, the default setting is "Enable". It is not necessary to change the
default setting for normal use.
When selecting multiple RAID groups as the target of this function, the contents of display vary
depending on the setting (Enable/Disable) for each RAID group. If all the settings point to the same
state, that state is displayed. If not, "Disable" is displayed for the ETERNUS DX80 S2/DX90 S2 or the
ETERNUS DX410 S2/DX440 S2, and "Enable" is displayed for the ETERNUS DX8100 S2/DX8700 S2.
• Throttle
When "Disk Tuning Parameter Setting" is enabled, specify the proportion of the number of
commands that is to be issued to a drive at the same time to the maximum number of command
issuance between 100% and 10%. The default throttle value is "100%" (the default number of
command issuance). It is not necessary to change the default value for normal use.
Specifying a low number limits the number of commands that are issued to a drive at the same
time, reducing the load for the specific RAID group (drive). This setting can be used when the
response performance of the specific RAID group (drive) is decreased due to a conflict between host
I/O or batch processes. Note that a low Throttle value decreases the number of commands that are
processed by the drive at the same time to avoid a long queue time.
• Ordered Cut
When "Disk Tuning Parameter Setting" is enabled, specify between 0 and 65535 for the number of
commands to optimize drive access processing (priority control).
The default value varies depending on the model. The default value is "0" for the ETERNUS DX80 S2/
DX90 S2 and the ETERNUS DX410 S2/DX440 S2, and "400" for the ETERNUS DX8100 S2/DX8700 S2.
When Ordered Cut is "x", the order is changed for every x commands based on the priority settings of
the commands. It is not necessary to change the default value for normal use.
When "Ordered Cut" is "0", the number of commands for controlling the priority cannot be specified.
All of the commands issued to the drive are processed according to their priority settings. The
Ordered Cut value cannot be used for SSDs.
Specifying a low value for Ordered Cut reduces the number of commands for priority control.
Commands with a lower priority are processed without delay. Note that by specifying a low value for
Ordered Cut, the priority control of commands is performed in increments for the specified number,
which might cause a delay in processing commands with a higher priority.