Raid 6 - Areca ARC-1110 User Manual

1.7.6 RAID 6

RAID 6 provides the highest reliability, but is not yet widely used.
It is similar to RAID 5, but it performs two different parity com-
putations or the same computation on overlapping subsets of
the data. RAID 6 can offer fault tolerance greater than RAID 1 or
RAID 5 but only consumes the capacity of 2 disk drives for dis-
tributed parity data. RAID 6 is an extension of RAID 5 but uses a
second, independent distributed parity scheme. Data is striped on
a block level across a set of drives, and then a second set of par-
ity is calculated and written across all of the drives.
Summary of RAID Levels
The SATA RAID controller supports RAID Levels 0, 1, 1E, 3, 5 and 6.
The table below provides a summary of RAID levels.
RAID Description
Level
0 Also known as stripping
Data distributed across multiple drives in
the array. There is no data protection.
1 Also known as mirroring
All data replicated on N separated disks.
N is almost always 2.
This is a high availability solution, but due
to the 100% duplication, it is also a costly
solution. Half of drive capacity in array
devoted to mirroring.
Features and Performance
Min.
Drives
1
2
INTRODUCTION
Data Data
Reliability Transfer
Rate
No data Very High
Protection
Lower Reads are
than RAID higher
6; than a
Higher single disk;
than
RAID 3, 5 Writes
similar to a
single disk
I/O Request
Rates
Very High for
Both Reads and Writes
Reads are twice as fast
as a single disk;
Write are similar to a
single disk.
29