NEC EXPRESS5800 User Manual page 34

Current Write Policy
This item indicates the status of the current write cache for this logical drive. The status varies
depending on the setting of write cache for each logical drive, setting of write cache for the
entire controller (Adaptive Writeback Cache), existence of battery connection and battery status
in the battery connection environment. For Adaptive Writeback Cache, see "3.5.2 Controller."
Setting of Adaptive
Writeback Cache
Disable
Enable
Settings tab
Alias Alias name
Read Policy Read Cache: Uses cache in reading.
Read Ahead: Uses cache in reading and provides read ahead. Improves
performance by read ahead before request.
No Cache: Does not use cache in reading.
Write Policy Write Through: Does not use cache in writing.
Write Back: Always uses cache in writing. It is expected that the setting can
improve write performance.
However, despite the setting, the actual write cache status may vary depending
on the setting of write cache for the controller (Adaptive Writeback Cache) and
the battery status. See the description of the Current Write Policy in the
Information tab in "3.5.9 Logical Drive" for details.
If you change either or both of the policies, click [Submit] to enable the change.
IMPORTANT: If you change an option for Read Policy,
it is validated immediately, regardless of clicking of
Submit or Reset button.
Background Activities tab
If you click the center of the Background Activities tab, the BGA being executed in the selected
disk array appears. Clicking the arrow at the right end of the tab allows the BGA start menu
items executable at the RAID level (including Initialize and Redundancy Check) to be displayed.
Battery status
No battery connected or
abnormal status
Battery connected and
normal status
No battery connected or
abnormal status
Battery connected and
normal status
Write Policy (setting of
write cache for each
logical drive)
Write Back
Write Through
Write Back
Write Through
Write Back
Write Through
Write Back
Write Through
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Current Write Policy
Write Back
Write Through
Write Back
Write Through
Write Through
Write Through
Write Back
Write Through