Areca ARC-1880 Series, User Manual

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APPENDIX
196
Summary of RAID Levels
6Gb/s SAS RAID controller supports RAID Level 0, 1, 10(1E), 3, 5, 6,
30, 50 and 60. The following table provides a summary of RAID levels.
RAID Level Comparsion
RAID
Level
Description Disks
Requirement
(Minimum)
Data
Availability
0 Also known as striping.
Data distributed across multiple
drives in the array. There is no data
protection.
1 No data
Protection
1 Also known as mirroring.
All data replicated on 2 separated
disks. N is almost always 2. Due to
this is a 100 % duplication, so is a
high costly solution.
2 Up to one disk
failure
10(1E) Also known as mirroring and striping.
Data is written to two disks
simultaneously, and allows an odd
number or disk. Read request can be
satisfied by data read from wither one
disk or both disks.
3 Up to one disk
failure in each
sub-volume
3 Also known Bit-Interleaved Parity.
Data and parity information is
subdivided and distributed across all
data disks. Parity information normally
stored on a dedicated parity disk.
3 Up to one disk
failure
5 Also known Block-Interleaved
Distributed Parity.
Data and parity information is
subdivided and distributed across all
disk. Parity information normally is
interspersed with user data.
3 Up to one disk
failure
6 RAID 6 provides highest reliability,
but not widely used. Similar to RAID
5, but does two different parity
computations or the same computation
on overlapping subsets of the data.
The RAID 6 can offer fault tolerance
greater that RAID 1 or RAID 5 but only
consumes the capacity of 2 disk drives
for distributed parity data.
4 Up to two disk
failure