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Chapter 2: RAID configuration
•
RAID Level:
The drop-down menu lists the possible RAID levels for the
virtual disk. Select RAID 10.
•
Strip Size:
The strip size specifies the size of the segment written to
each disk in a RAID configuration. You can set the strip size to 8, 16, 32,
64, 128, 256, 512 or 1024 Kbytes. A larger strip size produces higher
read performance. If your computer regularly performs random read
requests, choose a smaller strip size. The default is 64 Kbytes.
•
Access Policy:
Select the type of data access that is allowed for this
virtual disk:
◊
RW:
Allow read/write access.
◊
Read Only:
Allow read-only access. This is the default.
◊
Blocked:
Do not allow access.
•
Read Policy:
Specify the read policy for this virtual drive:
◊
Normal:
This disables the read ahead capability. This is the default.
◊
Ahead:
This enables read ahead capability, which allows the controller
to read sequentially ahead of requested data and to store the additional
data in cache memory, anticipating that the data will be needed soon.
This speeds up reads for sequential data, but there is little improvement
when accessing random data.
◊
Adaptive:
When Adaptive read ahead is selected, the controller
begins using read ahead if the two most recent disk accesses occurred
in sequential sectors. If the read requests are random, the controller
reverts to Normal (no read ahead).
•
Write Policy:
Specify the write policy for this virtual drive:
◊
WBack:
In Writeback mode the controller sends a data transfer
completion signal to the host when the controller cache has received
all the data in a transaction. This setting is recommended in Standard
mode.
◊
WThru:
In Writethrough mode the controller sends a data transfer
completion signal to the host when the disk subsystem has received all
the data in a transaction. This is the default.
◊
Wrthru for BAD BBU:
Select WBack for Write Policy and unselect this
item if you want the controller to use Writeback mode but the controller
has no BBU or the BBU is bad. If you choose this option, the controller
firmware automatically switches to Writethrough mode if it detects a bad
or missing BBU.
•
IO Policy:
The IO Policy applies to reads on a specific virtual disk. It
does not affect the read ahead cache.
