Areca ARC-1222 - HDD Read Ahead Cache; HDD Queue Depth; Stagger Power on; Auto Activate Incomplete Raid

WEB BROWSER-BASED CONFIGURATION
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• 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.
•
HDD Queue Depth
This parameter is adjusted the queue depth capacity of NCQ
(SATA HDD) or Tagged Command Queuing (SAS) which trans-
mits multiple commands to a single target without waiting for
the initial command to complete.
•
Stagger Power on
In a PC system with only one or two drives, the power can
supply enough power to spin up both drives simultaneously. But
in systems with more than two drives, the startup current from
spinning up the drives all at once can overload the power sup-
ply, causing damage to the power supply, disk drives and other
system components. This damage can be avoided by allowing
the host to stagger the spin-up of the drives. The SAS/SATA
drives have support stagger spin-up capabilities to boost reli-
ability. Stagger spin-up is a very useful feature for managing
multiple disk drives in a storage subsystem. It gives the host
the ability to spin up the disk drives sequentially or in groups,
allowing the drives to come ready at the optimum time without
straining the system power supply. Staggering drive spin-up
in a multiple drive environment also avoids the extra cost of a
power supply designed to meet short-term startup power de-
mand as well as steady state conditions.
Areca RAID controller has included the option for customer
to select the disk drives sequentially stagger power up value.
The values can be selected from 0.4s to 6s per step which
powers up one drive.
• Auto Activate Incomplete Raid
When some of the disk drives are removed in power off state
or boot up stage, the RAID set state will change to “Incomplete
State”. But if a user wants to automatically continue to work
while the SAS RAID controller is powered on, the user can set
the “Auto Activate Incomplete Raid” option to enable. The RAID
state will change to “Degraded Mode” while it powers on.