Dell PowerVault MD3220 - Manual (Page 102)

102 Configuration: Disk Groups and Virtual Disks
To change the virtual disk cache settings:
1 In the AMW, select the Logical tab and select a virtual disk
2 In the toolbar, select Virtual Disk Change Cache Settings.
The Change Cache Settings window is displayed.
3 Select one or more virtual disks.
To select nonadjacent virtual disks, press <Ctrl> click. To select adjacent
virtual disks, press <Shift> click. To select all of the available virtual disks,
click Select All.
4 In the Select cache properties area, you can select:
• Enable read caching—to enable read caching.
• Enable dynamic cache read prefetch—to enable dynamic cache read
prefetch.
• Enable write caching—to enable write caching.
•
Enable write caching with mirroring—to mirror cached data
across two redundant RAID controller modules that have the
same cache size.
• Enable write caching without batteries—to permit write caching
to continue even if the RAID controller module batteries are
discharged completely, not fully charged, or are not present.
CAUTION: Possible loss of data – Selecting the Enable write caching without
batteries option allows write caching to continue even when the batteries are
discharged completely or are not fully charged. Typically, write caching is turned
off temporarily by the RAID controller module until the batteries are charged. If you
select this option and do not have a universal power supply for protection, you
could lose data. In addition, you could lose data if you do not have RAID controller
module batteries and you select the Enable write caching without batteries
option.
NOTE: When the Optional RAID controller module batteries option is enabled,
Enable write caching is not displayed. The Enable write caching without
batteries is still available, but it is not checked by default.
NOTE: Cache is automatically flushed after the Enable write caching check
box is disabled.
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