9
2
STORAGE POLICIES
You can configure the
TowerRAID TR4UTP/TR4UT-BP
storage appliance to use any of the following storage policies to map
the appliance’s physical hard drives to virtual drives that are visible to the host computer. The virtual drives are called
volumes
. The host operating system treats each volume as if it were a single physical drive. This virtualization allows you to
overcome restrictions that are imposed by physical hard drives, such as speed, storage capacity or data storage reliability.
2.1
CLEAN MODE
The CLEAN MODE storage policy enables each hard drive to be seen separately as one drive. When using a SATA host
controller, CLEAN MODE should only be used if the SATA host controller provides Port Multiplier (PM) support. If a host
is not PM-aware, only a single drive is presented (drive 1). No such limitation if using a USB host connection.
The CLEAN MODE storage policy is available for a standalone (non-cascaded) storage or the top-level node of a cascaded
configuration, but not for subordinate nodes. Even though you can
use the MODE SWITCH to select CLEAN MODE for
any
node in a cascaded configuration, only the first
CLEAN MODE volume of any subordinate node is detected by your
host. Therefore, selecting CLEAN MODE for any subordinate node is not
recommended.
In a CLEAN MODE
configuration, the
TowerRAID TR4UTP/TR4UT-BP
storage appliance directly exposes each physical drive.
The CLEAN MODE will not clean up the drives partition if the drives were use as single drive before.
2.2
LARGE MODE
The LARGE MODE storage policy concatenates a series of physical hard drives as a single large volume; resulting in a
seamless expansion of virtual volumes
beyond the physical limitations of singularly connected hard drives.
TowerRAID
TR4UTP/TR4UT-BP
storage policy delivers maximum storage space without a single large capacity and costly hard drive.
Any node within a cascaded configuration can be set to LARGE MODE.
Hard drives 1 to 4 are concatenated into a single virtual volume
in the Figure below with a storage capacity that is equal to
the sum of each of the physical hard drives 1 to 4.
TR4UT / TR4UT-B
