Proware 2126JS6H-SQX, User Manual

Page: 31 / 292

NAS System
User’s Manual 31
7. The Virtual Drive Definition screen appears. You use this screen to select the
RAID level, stripe size, read policy and other attributes for the new virtual drives.
Virtual Drive Parameters and Descriptions
Parameter Description
RAID Level
The drop-down menu lists the possible RAID levels for the virtual
drive.
Stripe Size
The stripe size specifies the length of the data segments that the
RAID controller writes across multiple drives, not including parity
drives. For example, consider a stripe that contains 64 KB of
drive space and has 16 KB of data residing on each drive in the
stripe. In this case, the stripe size is 64 KB and the strip size is
16 KB. You can set the stripe size to 8, 16, 32, 64, 128, 256,
512, and 1024 Kbytes. A larger stripe size produces higher read
performance. If your computer regularly performs random read
requests, choose a smaller stripe size. The default is 64 Kbytes.
Access
Policy
Select the type of data access that is allowed for this virtual
drive:

RW: Allow read/write access. This is the default.

Read Only: Allow read-only access.

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
drive 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:

Always Write Back: In Writeback mode the controller sends
a data transfer completion signal to the host when the
controller cache has received all of the data in a transaction.
This setting is recommended in Standard mode.

Write Through: In Writethrough mode the controller sends a
data transfer completion signal to the host when the drive
subsystem has received all of the data in a transaction. This
is the default.