Sans Digital Mobileraid MR8X Detailed User's Manual page 61

SAS-to-SATA II RAID Subsystem
JBOD/RAID Configuration
The RAID subsystem supports JBOD and RAID configuration.
Maximum SATA Mode Supported:
The 8 SATA drive channels can support up to SATA ll, which runs up to 300MB/s. NCQ is a
command protocol in Serial ATA that can only be implemented on native Serial ATA hard
drives. It allows multiple commands to be outstanding within a drive at the same time.
Drives that support NCQ have an internal queue where outstanding commands can be
dynamically rescheduled or re-ordered, along with the necessary tracking mechanisms for
outstanding and completed portions of the workload. RAID subsystem allows user to
choose the SATA Mode: SATA150, SATA150+NCQ, SATA300, SATA300+NCQ.
HDD Read Ahead Cache:
This option allows the users to disable the cache of the HDDs on the RAID subsystem.
To some HDD models, disabling the cache in the HDD is necessary to prove the RAID
subsystem functions correctly.
Volume Data Read Ahead:
This option allows the users to set t he Volume Data Read Ahead function. Options are:
Normal, Aggressive, Conservative, and Disabled.
Stagger Power On Control:
This option allows the RAID subsystem's power supply to power up in succession
each HDD in the RAID subsystem. In the past, all the HDDs on the RAID subsystem are
powered up altogether at the same time. This function allows the power transfer time
(lag time) from the last HDD to the next one be set within the range of 0.4 to 6.0
seconds.
Spin Down Idle HDD (Minutes):
This option enables the hard drives to spin down after they become idle after a preset
period of time. Options are: Disabled, 1 (For Test), 3, 5, 10, 15, 20, 30, 40, and 60.
HDD SMART Status Polling:
The RAID subsystem can read HDD SMART information through this function. This
function is enabled by default.
Disk Write Cache Mode:
The RAID subsystem supports Disk Write Cache Mode options: Auto, Enabled, and Disabled. If
the RAID subsystem has BBM (battery backup module), selecting the Auto option will
automatically enable Disk Write Cache. On the other hand, if there is no BBM, the Auto option
will disable Disk Write Cache.
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Installation and Configuration Manual