NEC Storage Manager User Manual page 303

RAID
Redundancy
Level
RAID 0 None
Dual
RAID 1
configuration
RAID 5 Parity
RAID6 Double parity
Dual
RAID10
configuration
RAID50 Parity
*1: 100/1000/2000 series disk array: 1, 3, 5, 10, or 15 disks
*2: 100/1000/2000 series disk array: 4, 6, 8, 10, 12, or 14 disks
*3: S400/S1400/S2400/S2800 disk array: Not available for configuration
*4: S400/S1400/S2400/S2800 disk array: 5 disks
*5: S400/S1400/S2400/S2800 disk array: 6 or more disks (4+PQ) and 10 or more (8+PQ)
*6: S400/S1400/S2400/S2800 disk array: 4, 8, or 16 disks
*7: S400/S1400/S2400/S2800 disk array: 10 or 20 disks
Required
Decrease in
Number of
Capacity
PDs
1 or
None
*1, *3
more
2 50%
Equivalent
*4
3 or more to capacity
of 1 disk
Equivalent
to capacity
*5
6 or more
of 2/6 or
2/10 disks
4 or
50%
*2, *6
more
Equivalent
*7
10 or more to capacity
of 1/5 disks
13
Advantage
Quick access
High reliability
No performance
deterioration in reduced
state
Concurrent processing for
multiple R/W commands
The most reliable
(redundancy secured on a
failure of one physical disk)
Quick access
High reliability
No performance
deterioration in reduced
state
Concurrent processing for
multiple R/W commands
Quick access
Appendix C RAID
Disadvantage
Inaccessible when even a
single disk fails
Costly
Parity data read required
for writing
Performance deterioration
in reduced state
It is necessary to read
parity when writing data.
The accessibility to data
drops on degradation.
Costly
It is necessary to read
parity when writing data.
The accessibility to data
drops on degradation.