| RAID 0 (stripe) |
Raid level 0 splits data across drives, resulting in higher data throughput.
The performance of this RAID is great, but a loss of any drive in the array
will result in data loss. This level is commonly referred to as striping.
- Minimum number of drives required: 2
|
 |
| Advantages |
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- High performance
- Easy to implement
- No parity overhead
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| Disadvantages |
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| RAID 1 (mirror) |
RAID Level 1 writes all data to two or more drives. The performance of a level
1 array tends to be faster on reads and slower on writes compared to a single
drive, but if either drive fails, no data is lost. This is a good entry-level
redundant system, since only two drives are required; however, since one drive
is used to store a duplicate of the data, the cost per megabyte is high. This
level is commonly referred to as mirroring.
- Minimum number of drives required: 2
|
 |
| Advantages |
|
- Fault tolerant
- Easy to recover data in case of drive failure
- Easy to implement
|
| Disadvantages |
- 100% parity overhead
- Becomes very costly as number of disks increase
- Inefficient
|
| RAID 5 |
RAID Level 5 stripes data at a block level across several drives, with parity
equality distributed among the drives. The parity information allows recovery
from the failure of any single drive. Write performance is rather quick, but
because parity data must be skipped on each drive during reads, the
performance for reads tends to suffer. The low ratio of parity to data results
in low redundancy overhead.
- Minimum number of drives required: 3
|
 |
| Advantages |
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- High efficiency
- Fault tolerant
- The best choice in multi-user environments which are not write performance sensitive.
|
| Disadvantages |
- Disk failure has a medium impact on throughput
- Most complex controller design
|
| RAID 0+1 |
RAID Level 0+1 is a mirror (RAID 1) array whose segments are striped (RAID 0) arrays.
It is a great alternative for users that like the security of RAID 1 but need
some additional performance boost.
- Minimum number of drives required: 4
|
 |
| Advantages |
|
- Fault tolerant
- Very High I/O rates
|
| Disadvantages |
- Very expensive
- High overhead
- Very limited scalability
|
| RAID 10 |
RAID Level 10 is a striped (RAID 0) array whose segments are mirrored (RAID 1).
It is similar in performance to RAID 0+1, but with better fault tolerance and
rebuild performance.
- Minimum number of drives required: 4
|
 |
| Advantages |
|
- High fault tolerance
- High I/O rates
- Faster rebuild performance than RAID 0+1
- Under certain circumstances, RAID 10 array can sustain multiple simultaneous drive failures
|
| Disadvantages |
- Very expensive
- High overhead
- Very limited scalability
|
| RAID 50 |
RAID Level 50 is a striped (RAID 0) array which is striped across a RAID 5 array.
Performance is improved compared to RAID 5 because of the addition of the striped array.
Fault tolerance is also improved.
- Minimum number of drives required: 6
|
 |
| Advantages |
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- Higher fault tolerance than RAID 5
- Higher efficiency than RAID 10
- Higher I/O rates
|
| Disadvantages |
- Very complex and expensive to implement
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