| RAID-0 |
This technique
has striping but no redundancy of data. It
offers the best performance but no fault-tolerance
(i.e. if a drive fails you lose all your data).
|
| RAID-1 |
This type is also known
as disk mirroring
and consists of at least two drives that duplicate
the storage of data. There is no striping.
Read performance is improved since either drive can
be read at the same time. Write performance is the
same as for single disk storage. RAID-1 provides the
best performance and the best fault-tolerance in a
multi-user system. |
| RAID-2 |
This type uses striping
across disks with some disks storing error checking
and correcting (ECC)
information. |
| RAID-3 |
RAID level
3 stripes data across multiple drives, with an additional
drive dedicated to parity, for error correction/recovery.
RAID 3 is not found on all controllers. |
| RAID-4 |
This type uses large
stripes, which means you can read records from any
single drive. This allows you to take advantage of
overlapped I/O for read operations. Since all write
operations have to update the parity
drive, no I/O overlapping is possible. |
| RAID-5 |
RAID level 5 is the
most popular configuration, providing striping as
well as parity for error recovery. In RAID 5, the
parity block
is distributed among the drives of the array, giving
a more balanced access load across the drives. The
parity information is used to recover the data if
one drive fails, and is the main reason this method
is the most popular.The disadvantage is a relatively
slow write cycle. |
| RAID-6 |
This type is similar
to RAID-5 but includes a second parity
scheme that is distributed across different drives
and thus offers extremely high fault- and drive-failure
tolerance. |
| RAID-7 |
This type includes a
real-time embedded operating system as a controller,
caching via a high-speed bus, and other characteristics
of a stand-alone computer. |
| RAID-10 |
This type offers an
array of stripes in which each stripe is a RAID-1
array of drives. This offers higher performance than
RAID-1 but at much higher cost. |
| RAID-53 |
This type offers an
array of stripes in which each stripe is a RAID-3
array of disks. This offers higher performance than
RAID-3 but at much higher cost. |
