DF-7506 1-to-2 SATA II RAID Box
10
User Manual
RAID 1 (SAFE)
RAID 1 (also called Mirroring) is the replication of data onto
the other hard disk in real time to ensure continuous data
availability. In a RAID 1 system with two hard disks, the
data in one hard disk will be exactly the same as the data in
the other hard disk.
The capacity of the RAID 1 volume will be equivalent to the
size of one drive (if both drives are the same) or the smaller
of the two drives (if they are different).
RAID 1 provides that highest level of data protection. Failure
in one hard disk will cause the RAID 1 volume to enter into
degraded mode. The host controller can still read/write data
to the volume without knowing any hard disk failure. When
the failed hard disk is replaced, an on-line rebuild will be
started automatically to restore data redundancy.
Although the volume remains accessible during rebuild process, the volume is
susceptible to data loss through damage to the remaining drive until redundancy is
restored at the end of the rebuild and verification process. Host access takes precedence
over the rebuild process. If the volume is continually used during the rebuild, the rebuild
process will take a longer time to complete, and the host data transfer performance will
also be affected.
SAFE 33
The SAFE33 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 m
irroring) but you don’t need high reliability for the
remainder of your data. SAFE33 reduces the cost of additional hard drives in operations
where non-critical data could be lost without severe consequences.
SAFE33 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.
