Rosewill R2-RAID - Manual (Page 15)

Server RAID System [ R2-RAID ] User Manua
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RAID / SAFE33 ：It creates
two virtual volumes; one
SAFE volume and one BIG
volume, and should be
used when you need the
high reliability for some of
your data but you don’t
need high reliability for the
remainder of your data. It
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.
When using a SATA host connection, you must have a PM (Port Multiplier)
aware host adapter when using SAFE33 on the top level node of a cascaded
configuration so that ALL 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. No such limitation exists when
using a USB host connection.
The size of the SAFE volume 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.
Drive A
250GB
Drive B
250GB
HD3206SRD
Port 0 Port 1
Safe
83GB
Equal hard drives
Drive A
250GB Drive B
750GB
HD3206SRD
Port 0 Port 1
Big
334GB
Safe
83GB
Big
834GB
Unequal hard drives