Installation guide

Software Operation Manual
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subsystem allows the user to select the SATA NCQ support: “Enabled” or
“Disabled”.
3.7.5.7 HDD Read Ahead Cache
Allow Read Ahead (Default: Enabled)—When “Enabled”, the drive’s read ahead
cache algorithm is used, providing maximum performance under most
circumstances.
3.7.5.8 Volume Data Read Ahead
The Read data ahead parameter specifies the controller firmware algorithms
which process the Read Ahead data blocks from the disk. The read ahead
parameter is normal by default. To modify the value, you must know your
application behavior. The default normal option satisfies the performance
requirements for a typical volume. The disabled value implies no read ahead.
The most efficient value for the controllers depends on your application.
Aggressive read ahead is optimal for sequential access but it degrades random
access.
3.7.5.9 Disk Write Cache Mode
Disk cache can be turned off to prevent data lost, turned on to increase the
performance of the machine. The following is the reason why a user might want
to turn off the cache. In case of power failure, the data stored in the disk cache
waiting to be process might be lost. The disadvantage to turn off the disk cache
is that performance will decrease dramatically.
Auto: Disk cache's setting will accord the installation of battery backup. When
battery backup is installed, Disk cache is disabled. No battery backup installed,
Disk cache is enabled.
To set or change the configuration, press the UP/ DOWN to select “Disk Write
Cache Mode” and then press the ENT to accept the selection.
3.7.5.10 Disk Capacity Truncation Mode
The RAID subsystem use drive truncation so that drives from differing vendors
are more likely to be able to be used as spares for each other. Drive truncation
slightly decreases the usable capacity of a drive that is used in redundant units.
The RAID subsystem provides three truncation modes in the system
configuration: “Multiples Of 10G”, “Multiples Of 1G” and “Disabled”.
Multiples Of 10G: If you have 120 GB drives from different vendors; chances
are that the capacity varies slightly. For example, one drive might be 123.5 GB,
and the other 120 GB. “Multiples Of 10G” truncates the number under tens. This
makes the same capacity for both of these drives so that one could replace the
other.
Multiples Of 1G: If you have 123 GB drives from different vendors; chances are
that the capacity varies slightly. For example, one drive might be 123.5 GB, and