RAID Level Comparison

RAID 0 - Mechanism: striping (data division without redundancy)
Description: Data is divided into fragments and written in parallel to multiple disks.

Advantages:

  • very high performance (read and write),
  • full utilization of disk capacity.

Disadvantages:

  • no redundancy,
  • single disk failure = loss of all data.


Application: systems where only performance matters (e.g., cache, temporary data).

RAID 1 (mirroring) - capacity 50% (or less)
Description: Data is copied identically to two (or more) disks.

Advantages

  • high reliability,
  • simple data reconstruction,
  • fast read speed.

Disadvantages:

  • only 50% of the space is used,
  • higher cost relative to capacity.

Application: operating systems, sensitive data. Each drive has its own copy – half of the space is used for redundancy. Note:
With more drives, multiple mirroring configurations are possible, but the principle remains: high capacity loss = high reliability.


RAID 5 - "1 drive for parity"
Description: Data and parity are distributed across at least three disks.

Advantages:

  • good compromise between performance and security,
  • efficient space utilization.

Disadvantages:

  • slower writes (parity calculation),
  • long rebuild time,
  • risk with large disks (during rebuild).


Applications: file servers, general environments. The equivalent of one drive is dedicated to parity data (distributed across all drives). Good efficiency (e.g., 75% with 4 drives), increases with the number of drives. 

RAID 6 - "2 drives for parity"
Description: Similar to RAID 5, but with double parity.

Advantages:

  • high fault tolerance,
  • safe with large arrays.

Disadvantages:

  • even slower writes than RAID 5,
  • higher hardware requirements.


Applications: critical systems, archives. Two "disks" (logically) are dedicated to backup data. Greater security. Lower efficiency than RAID 5.

RAID 10 (1+0) - efficiency 50% (but faster and safer than RAID 1 in practice)
Description: A combination of RAID 1 and RAID 0 (mirroring + striping).

Advantages:

  • very high performance,
  • high fault tolerance,
  • fast rebuild.


Disadvantages:

  • 50% capacity loss,
  • requires more disks.


Applications: databases, high-performance systems.

RAID 0+1 - efficiency also 50%m poorer fault tolerance.
Description: First striping, then mirroring (the inverse of RAID 10).

Advantages:

  • good performance,
  • data redundancy.

Disadvantages:

  • lower resilience than RAID 10;
  • if one disk fails, half the array is at risk.


Applications: less commonly used, replaced by RAID 10. Why? Efficiency is the same as RAID 10, but with poorer fault tolerance.

RAID 50 (RAID 5 + 0) efficiency depends on groups. Mechanism: RAID 5 in groups + striping
Description: Combination of several RAID 5 groups into RAID 0.

Advantages:

  • better performance than RAID 5,
  • higher resilience than a single RAID 5.

Disadvantages:

  • more complex configuration,
  • more expensive.


Applications: large file servers, NAS systems. Each RAID 5 group "loses" 1 disk to parity.

RAID 60 (RAID 6 + 0) – even more redundancy
Description: Combination of RAID 6 and RAID 0.

Advantages:

  • very high fault tolerance,
  • good performance for large data sets.

Disadvantages:

  • high cost,
  • complex management.

 
Applications: data centers, critical systems. Each RAID 6 group loses 2 drives to parity.

The table below compares the advantages and disadvantages of various RAID arrays, assuming our server has 8 drives, each with a capacity of (X) - 1 TB.

N - number of discs.
X- capacity 

RAID version Min. Number of Discs Max. Failures
Without Data Loss		 Performance Security Storage Efficiency Comparison Usable capacity
(8x1TB)
RAID 0
(N × X)		 2 0 ***** X 100% 8 TB
RAID 1
(N/2) × X
 2 1 *** ***** 50% 4 TB
RAID 5
(N-1) × X
 3 1 *** *** ~87% 7 TB
RAID 6
(N-2) × X
 4 2 ** **** 75% 6 TB
RAID 10
(N/2) × X
 4 even few * ***** ***** 50% 4 TB
RAID 0+1
(N / 2) × X
 4 1 ***** *** 50% 4 TB
RAID 50
(N - group) × X
 6 ≥ 1 (per group) **** ****  ~67–80% 6 TB
RAID 60
(N - 2×grous) × X
 8 ≥ 2 (per group) **** ***** 50-75% 4-6 TB

* RAID 10: Can survive more than one failure, as long as the failures do not involve the same mirrored pair.

Summary

  • Best space utilization: RAID 0 (but lacking security)
  • Best compromise: RAID 5 (small/medium systems)
  • Safer for large drives: RAID 6
  • Least efficient, but fast and secure: RAID 10
  • Scalable solutions: RAID 50 and 60