Types of RAID
There are at least nine types of RAID plus a non-redundant array (RAID-0):
RAID 0 (Striping / Span)
- Scripting with no redundancy.
- Best performance but no fault tolerance.
RAID 2 (Mirroring)
- At least 2 drives are used to duplicate the storage of data.
- No scripting.
- Read performance is improved as either disk can be read at the same time.
- Provides the best performance and the best fault-tolerance in a multi-user system.
- This type uses striping and dedicates one drive to storing parity information.
- The embedded error checking (ECC) information is used to detect errors.
- Cannot overlap I/O.
- Best for single-user systems with long record applications.
RAID 4 (Striping with Parity)
- Uses block-level striping with a dedicated parity disk.
- This allows you to take advantage of overlapped I/O for read operations
- No I/O overlapping is possible, since all write operations have to update the parity drive.
- Includes a rotating parity array reducing the write limitation in RAID 4.
- All read and write operations can be overlapped.
- Stores parity information but not redundant data
- Requires at least three and usually five disks for the array.
- Best for multi-user systems in which performance is not critical or which do few write operations.
- Similar to RAID-5 but includes a second parity scheme that is distributed across different drives.
- Offers extremely high fault and drive failure tolerance.
RAID 10 (Striping with Mirroring (RAID 0 + 1 ))
- Scripting and mirroring combined