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LaCie RAID Technology White Paper
RAID 1
RAID 1 (also called SAFE mode in some LaCie devices) is a secure RAID mode that requires at least 2 drives
and works with pairs of drives. One logical volume mounts on the computer and the combined available
capacity of both drives is limited to the capacity of the lowest-capacity disk. If one physical disk fails, the data
is available immediately on the second disk. No data is lost if one disk fails.
Applications
RAID 1 provides maximum data safety in the
event of a single disk failure, but because data
is written twice, performance is reduced slight-
ly when writing. RAID 1 is a good choice when
safety is more important than speed.
LaCie Products with RAID 1
LaCie 2big quadra
✦
LaCie 2big network
✦
RAID 1
A1
B1
C1
D1
E1
A1
B1
C1
D1
E1
How RAID 1 Capacity Is Calculated
Each disk in a RAID 1 system should have the
same capacity.
Storage capacity in a RAID level 1 configuration
is calculated by multiplying the number of drives
by the disk capacity and dividing by 2, or
C = n*d/2
where:
C = available capacity
n = number of disks
d = disk capacity
For example, in a RAID 1 array with four drives
each with a capacity of 1000GB, the total ca-
pacity of the array would be 2000GB:
C = (4*1000)/2
RAID 0
RAID 1
RAID 3
RAID 3+Spare
RAID 5
RAID 5+Spare
RAID 6
RAID 0+1
RAID 10
Concatenation
JBOD
RAID Selection
