DF-7506 1-to-2 SATA II RAID Box
User Manual
11
The size of the SAFE volume of a SAFE33 RAID mode will be one-third of the size of one
hard drive (if they are equal) or one-third of the size of the smaller (if they are not
equal.) The size of the BIG volume will be the combination of all remaining capacities.
For example: if there are two 300GB hard drives used in SAFE33 RAID mode, the
capacity of the SAFE volume will be 100GB (1/3 of 300GB) and the BIG volume will be
400GB (the remaining capacity after allocating 100GB from each hard drive).
A SATA host connection must have a PM (Port Multiplier) aware host adapter when using
SAFE33 so that the two volumes can be detected by the host. If your SATA host adaptor
is not PM aware, then ONLY the SAFE volume will be detected and the BIG volume will
not be accessible.
SAFE 50
The SAFE50 RAID mode creates
two virtual volumes
; one
SAFE (RAID 1)
volume and
one
BIG
volume, and should be used when you need the high reliability for some of your
data (with the added overhead of mirroring) but you don’t need high reliability for the
remainder of your data. SAFE50 reduces the cost of additional hard drives in operations
where non-critical data could be lost without severe consequences.
SAFE50 uses a SAFE volume that is mirrored across two hard drives to protect your
critical data in the event a hard drive failure. If one drive fails the SAFE volume is
retrievable although the BIG volume is not. When you replace the failed drive, the SAFE
volume is automatically rebuilt on to the replacement drive.
For example, if you are using a video editing application that stores the primary source
data and also uses some temporary storage for editing, you need protected storage that
is offered by SAFE for the primary source data, but you do not need protected storage
for the temporary data. Therefore, the combination of SAFE and BIG would be the most
efficient utilization of your available storage capacity. If either hard drive fails the
primary data stored on the SAFE volume would still be available whereas the temporary
data stored on the BIG volume would be lost.
The size of the SAFE volume of a SAFE50 RAID mode will be one-half of the size of one
hard drive (if they are equal) or one-half of the size of the smaller (if they are not equal).
The size of the BIG volume will be the combination of all remaining capacities.
For example: if there are two 300GB hard drives used in SAFE50 RAID mode, the
capacity of the SAFE volume will be 150GB (1/2 of 300GB) and the BIG volume will be
300GB (the remaining capacity after allocating 150GB from each hard drive).
A SATA host connection must have a PM (Port Multiplier) aware host adapter when using
SAFE50 so that the two volumes can be detected by the host. If your SATA host adaptor
is not PM aware, then ONLY the SAFE volume will be detected and the BIG volume will
not be accessible.
