LaCie FIREWIRE 800/400 - Manual (Page 20)

LaCie Biggest Quadra
User Manual page
Understanding RAID
3.4. RAID 5 + Hot Spare
This level is the same as RAID 5, but one disk is des-
ignated as a “Hot Spare,” which means that in the event of
a disk failure, the “Hot Spare” disk would automatically be
activated to replace the failed disk.
The storage capacity of a RAID 5+ Hot Spare array fol-
lows the same logic as that of RAID 5, but with the dif-
ference being that there is one less disk in the array. So, for
instance, if there was a RAID 5+ Hot Spare array with three
drives of varying capacities of 40GB, 50GB and 60GB, and
one disk designated as the hot spare with a capacity of 70GB,
the total capacity of the array would be 80GB [2 (3 disks – 1
disk) x 40 = 80].
This diagram represents a
RAID 5 array, consisting of
four disks, which are
connected to the Controller.
Parity blocks are represented
by the letter P.
E
D
C
B
A
CONTROLLER
A
C
P
EF
G
B
H
P
CD
E F
P
AB
P
GH
D
"
/
-
*
,
Fig. 3.4.