RAID types
RAID Levels, also known as "Redundant Array of Independent Disks" levels, represent different methods of organizing
data within a RAID array, each offering varying speeds and fault tolerance properties.
RAID levels 0, 1, 1E, 5, 50, 6, 60, and 1+0 provide different degrees of fault tolerance.
In the event of a hard drive failure in the array, data is dynamically reconstructed without any interruption in access.
RAID levels 2, 3, and 4 are theoretically defined but not practically used.
More complex configurations, such as RAID 5E/5EE and RAID DP, incorporate additional features
but fall beyond the scope of this reference.
RAID Levels Comparison Table:
| RAID Level |
Min Number of Disks |
Fault Tolerance |
Disk Space Overhead |
Read Speed |
Write Speed |
Hardware Cost |
| RAID 0 |
2 |
None |
None |
Fast |
Fast |
Cheap |
| RAID 1E |
3 |
1 disk |
50% |
Fast |
Fair |
High (disks) |
| RAID 1 |
2 |
1 disk |
50% |
Fast |
Fair |
High (disks) |
| RAID 5 |
2 |
1 disk |
1 disk |
Fast |
Slow |
High |
| RAID 50 |
6 |
1 disk |
2 disk |
Fast |
Slow |
Very High |
| RAID 6 |
4 |
2 disk |
2 disk |
Fast |
Slow |
Very High |
| RAID 60 |
8 |
2 disk |
4 disk |
Fast |
Slow |
Very High |
| RAID 10 |
4 |
1 disk per RAID0 |
50% |
Fast |
Slow |
Expensive |
RAID Level Summaries:
- RAID 0 (Stripe set): Offers high performance for non-critical data. No fault tolerance;
failure of any disk results in the loss of all data.
- RAID 1E: A mirror over an odd number of disks, providing reliability with 50% capacity overhead.
- RAID 1 (Mirror): Reliable storage for smaller capacity, using mirroring to store identical copies of data on two drives.
- RAID 5 (Stripe with parity): Suitable for large, reliable, and relatively cheap storage.
Provides fault tolerance by writing parity blocks, allowing recovery from a single disk failure.
- RAID 50 (RAID5 arrays combined in a RAID0): Combines multiple RAID5 arrays into a RAID0 for increased performance.
Survives a single disk failure in each RAID5 array.
- RAID 6 (Stripe with dual parity): Large, highly reliable, and relatively expensive storage.
Uses dual parity functions to withstand two drive failures.
- RAID 60 (RAID6 arrays combined into a RAID0): Similar to RAID50 but uses RAID6 arrays.
Survives two disk failures across different RAID6 arrays.
- RAID 10 (Mirror over stripes): Large, fast, and reliable but expensive storage.
Uses two identical RAID0 arrays for fault tolerance and increased read speed.
Each RAID level has its strengths and weaknesses, catering to specific needs based on performance,
fault tolerance, and cost considerations.
To select the optimal array level, please use a special RAID calculator .