Redundant Array of Independent Disks (RAID)

RAID 1:

RAID is a technology that employs the simultaneous use of two or more partitions on the same or different hard disk drives to achieve greater levels of performance and reliability.

It is a fault tolerance mechanism in which the data is not lost even if one of the disk fails.

Types of RAID

• Hardware RAID
• Software RAID

RAID Levels

• RAID 0 (striping without parity)
• RAID 1 (disk mirroring)
• RAID 5 (striping with parity)
• RAID 10 (mirroring with striping)

RAID 0

1. Minimum 2 hard disks required.
2. Can support maximum 32 hard disks.
3. Data is written simultaneously and evenly across the multiple hard disks.
4. The reading and writing speed is faster.
5. Fault tolerance is not available.

RAID 1:

1. Works with only 2 hard disks.
2. Same data is simultaneous written on both the disk.
3. The reading speed is fast and the writing speed is slow.
4. Fault tolerance is available.
5. Overhead is 50%

RAID 5:

1.  Minimum 3 hard disks required.
2.  Can support maximum 32 hard disks.
3.  Data is written simultaneously and evenly across multiple hard disks.
4.  The parity is written equally on all disks.  
5. The reading and writing speed is fast.
6.  Fault tolerance is available.

RAID 10:

1. It requires at least 4 drives