User manual

INTRODUCTION
21
Summary of RAID Levels
SATA RAID controller supports RAID Levels 0, 1, (10), 3, 5 and 6. Table
below provides a summary of RAID levels.
Features and Performance
RAID
Level
Description Min.
Drives
Data
Reliability
Data
Transfer
Rate
I/O Request
Rates
0 Also known as stripping
Data distributed across multiple drives in
the array. There is no data protection
1 No data
Protection
Very High Very High for
Both Reads and Writes
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.
2 Lower
than RAID
6;
Higher
than
RAID 3,5
Reads are
higher
Than a
single disk;
Writes
similar to a
single disk
Reads are twice faster
than a single disk;
Write are similar to a
single disk.
10 Also known Block-Interleaved Parity.
Data and parity information is subdivided
and distributed across all disk. Parity must
be the equal to the smallest disk capacity
in the array. Parity information normally
stored on a dedicated parity disk.
3 Lower
than RAID
6;
Higher
than
RAID 3,5
Transfer
rates more
similar
to RAID
1 than
RAID 0
Reads are twice faster
than a single disk;
Writes are similar to a
single disk.
3 Also known Bit-Interleaved Parity.
Data and parity information is subdivided
and distributed across all disk. Parity must
be the equal to the smallest disk capacity
in the array. Parity information normally
stored on a dedicated parity disk.
3 Lower
than RAID
1, (10),
6;
Higher
than a
single
drive
Reads are
similar to
RAID 0;
Writes are
slower
than a
single disk
Reads are similar twice
faster than a single
disk;
Writes are similar to a
single disk.
5 Also known Block-Interleaved Distributed
Parity.
Data and parity information is subdivided
and distributed across all disk. Parity must
be the equal to the smallest disk capacity
in the array. Parity information normally
stored on a dedicated parity disk.
3 Lower
than RAID
1, (10),
6;
Higher
than a
single
drive
Reads are
similar to
RAID 0;
Writes are
slower
than a
single disk
Reads are similar to
RAID 0;
Writes are slower than
a single disk.
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 tol-
erance greater that RAID 1 or RAID 5 but
only consumes the capacity of 2 disk drives
for distributed parity data.
4 highest
reliability