User`s guide

4-52
Parameters for VD Definition
Listed below are parameters for Configuration Wizard.
Item Parameter Remarks
RAID Level
RAID 0 / RAID 1 / RAID 5 / RAID 6 /
RAID 00 / RAID 10 / RAID 50 /
RAID60
RAID 00 and RAID 60 are not
supported.
Strip Size
8 KB / 16 KB / 32 KB / 64 KB / 128 KB
/ 256 KB / 512 KB / 1024 KB
Recommended value: 64KB
Access Policy
RW / Read Only / Blocked
Recommended value: RW
Read Policy
Normal / Ahead / Adaptive
Recommended value: Normal
Write Policy
WBack / WThru
WBack: WriteBack
WThru: WriteThru
WrtThru for
BAD BBU
Checked / Unchecked Select a mode when WriteBack is
specified for Write Policy.
Checked: Normal WriteBack
Unchecked: Constant WriteBack
Recommended value: Checked
IO Policy
Direct / Cached
Recommended value: Direct
Disk Cache
Policy
NoChange / Enable / Disable
Recommended value: Disable
Disable BGI
No / Yes Specify whether to perform
Background Initialize after creation of
VD.
Recommended value: No
IMPORTANT:
 BGI (Back Ground Initialize) is available only for a RAID5 VD configured with five or
more HDDs or a RAID6 VD configured with seven or more HDDs.
 To use RAID 5 or RAID 6, you need to install the optional RAID Upgrade Kit.
 If no optional RAID Upgrade Kit is installed, do not select the "RAID5" option that
may appear in the [RAID Level] box. If you select it, you will fail to save the
configuration information, and you will need to define a VD again from the start.
The Write Policy includes the following modes depending on the combination with WrtThru for BAD BBU. Select a
mode suitable for your environment.
WrtThru for BAD BBU
Checked Unchecked
WBack
Normal write back mode
(recommended)
This mode is available only when the
additional battery backup is installed.
The controller uses the cache
memory for writing.
However, if the battery is being
charged or failed, the controller
operates automatically in WThru
(write through) mode. Thus, this
mode can provide higher data
security.
Constant write back mode
This mode is available even if the
additional battery backup is not
installed.
The controller uses the cache memory
for writing. In this mode, the data in
cache memory is not protected from
damage if a power failure occurs due to
a charged/discharged or defective
battery. Be sure to use a UPS when
specifying this mode for write policy.
Write
Policy
WThru Write through mode
This mode is recommended when
the additional battery backup is not
installed.
The controller does not use cache
memory to write the data.
* This mode is unavailable.
If you do not check "WrtThru for BAD
BBU" at the creation of VD, this item is
automatically checked after the VD has
been created.