LaCie 5big Network 2
• DESIGN BY NEIL POULTON
Administering Your LaCie 5big Network 2
User Manual
page 54
4.17.2. About RAID Modes
Refer to the table below for an overview of the different RAID modes,
and see the descriptions for details.
RAID Mode
Capacity
Protection
RAID 5 (default)
80%
RAID 5+Spare
60%
RAID 6
60%
RAID 10*
50%
RAID 0
100%
RAID 1**
50%
RAID5:
In RAID 5, data is striped across all disks (minimum of three)
and a parity block for each data block (P in
Fig. 78
) is written on the
same stripe. If one physical disk fails, the data from the failed disk
can be rebuilt onto a replacement disk. No data is lost in the case
of a single disk failure, but if a second disk fails before data can be
rebuilt to a replacement drive, all data in the array will be lost.
RAID5+Spare:
RAID 5+Spare is a RAID 5 array in which one disk is
used as spare to rebuild the system as soon as a disk fails (
Fig. 79
).
At least four disks are required. If one physical disk fails, the data
remains available because it is read from the parity blocks. Data
from a failed disk is rebuilt onto the hot spare disk. When a failed
disk is replaced, the replacement becomes the new hot spare. No
data is lost in the case of a single disk failure, but if a second disk
fails before the system can rebuild data to the hot spare, all data in
the array will be lost.
RAID6:
In RAID 6, data is striped across all disks (minimum of four)
and a two parity blocks for each data block (p and q in
Fig. 80
) is
written on the same stripe. If one physical disk fails, the data from
the failed disk can be rebuilt onto a replacement disk. This Raid
mode can support up to two disk failures with no data loss. RAID 6
provides for faster rebuilding of data from a failed disk.
continued on the next page >>
Fig. 78
Fig. 79
K:B=.
Disk 1
Disk 2
Disk 3
Disk 4
Disk 5
A2
B2
D1
Cp
A1
B1
C1
D1
Ep
A2
B2
C2
Dp
E1
A3
C2
D2
Bp
B3
C3
D3
A3
B3
Cp
D2
E2
A4
Bp
C3
D3
E3
Ap
B4
C4
D4
E4
K:B=.$LiZk^
Disk 1
Disk 2
Disk 3
Disk 4
Disk 5
B2
D1
Cp
A1
B1
C1
DP
A3
C2
D2
Bp
B3
A3
D2
Ap
C3
D3
Spare
A2
Fig. 80
K:B=/
Disk 1
Disk 2
Disk 3
Disk 4
Disk 5
Ap
Bq
C3
D3
Aq
B3
C3
D3
A3
Cq
D2
Bp
A2
B2
Dq
Cp
A1
B1
C1
Dp
* RAID 10 is only available if there are four disks installed in the 5big Net-
work 2.
** RAID 1 is only available if there are two disks installed in the 5big Network
2.
