Dwg: Article written and Venn diagram created.

2026-01-02T22:54:53Z

Article written and Venn diagram created.

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== RAID 5 vs. RAID 6 ==
RAID 5 and RAID 6 are levels of RAID (Redundant Array of Independent Disks) that use disk striping with parity to protect data.<ref name="ref1" /><ref name="ref2" /> Both distribute data and parity information across multiple hard drives to provide fault tolerance, but they differ fundamentally in their level of redundancy and performance characteristics.<ref name="ref3" /> RAID 5 requires a minimum of three disks and can withstand the failure of a single drive without data loss.<ref name="ref4" /><ref name="ref5" /> RAID 6 requires at least four disks and adds a second independent parity block, allowing it to tolerate the failure of up to two drives simultaneously.<ref name="ref2" />

The choice between RAID 5 and RAID 6 involves a trade-off between cost, storage efficiency, performance, and the desired level of data protection. While both offer good read performance, the additional parity calculation in RAID 6 results in slower write performance compared to RAID 5.

=== Comparison Table ===
{| class="wikitable"
|-
! Category !! RAID 5 !! RAID 6
|-
| '''Minimum Drives''' || 3<ref name="ref5" /> || 4
|-
| '''Fault Tolerance''' || Can withstand a single drive failure.<ref name="ref3" /> || Can withstand up to two simultaneous drive failures.<ref name="ref3" />
|-
| '''Storage Efficiency''' || Usable capacity is the total capacity of all drives minus the capacity of one drive.<ref name="ref1" /> For example, with five 1 TB drives, usable capacity is 4 TB.<ref name="ref1" /> || Usable capacity is the total capacity of all drives minus the capacity of two drives. A four-drive array with 1 TB disks yields 2 TB of usable space.
|-
| '''Write Performance''' || Slower than RAID 0 or RAID 1 due to parity calculations.<ref name="ref5" /> Generally faster than RAID 6 because only one parity set is written. || Slower than RAID 5 because it calculates and writes two separate parity blocks for all data.
|-
| '''Read Performance''' || Fast, as data is read from multiple disks concurrently.<ref name="ref3" /> || Also fast and comparable to RAID 5, as data is striped across multiple disks.<ref name="ref3" />
|-
| '''Rebuild Performance''' || Faster rebuild times compared to RAID 6. The process puts stress on the remaining drives. || Rebuilds are slower due to the need to recalculate two sets of parity data. However, the array remains protected if another drive fails during the rebuild.
|-
| '''Common Use Cases''' || File and application servers with a limited number of drives.<ref name="ref1" /> Suitable for data warehousing and environments where read speeds are a priority.<ref name="ref5" /> || Mission-critical applications, enterprise backup systems, and large archival systems where data integrity is paramount. Recommended for arrays with large-capacity drives where rebuild times are longer.
|}

[[File:Venn_diagram_Differences_between_RAID-5-_versus_RAID-6_comparison.png|thumb|center|800px|alt=Venn diagram for Differences between RAID-5- and RAID-6|Venn diagram comparing Differences between RAID-5- and RAID-6]]

=== Fault Tolerance and Data Protection ===
The most significant difference between the two levels is their ability to handle drive failures. RAID 5 uses a single distributed parity block, which allows it to reconstruct the data from a single failed drive. If a second drive fails before the first one is replaced and the array is rebuilt, all data in the array will be lost.<ref name="ref5" />

RAID 6 enhances data protection by using two independent distributed parity blocks. This dual parity enables the array to remain operational and maintain data integrity even after two simultaneous drive failures. This makes RAID 6 a more robust solution for critical data, especially in large arrays where the probability of a second drive failure during the lengthy rebuild process of the first is higher.

=== Performance Implications ===
Both RAID 5 and RAID 6 offer excellent read performance because data is striped across multiple disks, allowing for parallel read operations.<ref name="ref3" /> However, their write performance is impacted by the need to calculate and write parity information.

RAID 5 incurs a write penalty because each write operation requires reading the old data, reading the old parity, writing the new data, and writing the new parity. RAID 6 suffers from a more significant write penalty because it must perform calculations for and write two sets of parity data for every write operation. Consequently, RAID 6 generally has slower write performance than RAID 5.

=== Storage Efficiency and Cost ===
RAID 5 is more space-efficient than RAID 6. In a RAID 5 array, the storage capacity equivalent to one disk is used for parity information. In a RAID 6 array, the capacity of two disks is dedicated to parity. For an array with 'N' drives, the usable capacity in RAID 5 is (N-1) times the capacity of a single drive, whereas in RAID 6 it is (N-2). This means that for the same number of drives, RAID 5 offers more usable storage space. The higher fault tolerance of RAID 6 comes at the cost of reduced storage capacity and the requirement of at least one additional drive.

== References ==
<references>
<ref name="ref1">[https://www.techtarget.com/searchstorage/definition/RAID-5-redundant-array-of-independent-disks "techtarget.com"]. Retrieved January 02, 2026.</ref>
<ref name="ref2">[https://en.wikipedia.org/wiki/Standard_RAID_levels "wikipedia.org"]. Retrieved January 02, 2026.</ref>
<ref name="ref3">[https://www.stellarinfo.com/blog/raid-5-vs-raid-6/ "stellarinfo.com"]. Retrieved January 02, 2026.</ref>
<ref name="ref4">[https://www.techtarget.com/searchdatabackup/tip/RAID-5-vs-RAID-6-Capacity-performance-durability "techtarget.com"]. Retrieved January 02, 2026.</ref>
<ref name="ref5">[https://www.diskinternals.com/raid-recovery/raid-rebuild-time/ "diskinternals.com"]. Retrieved January 02, 2026.</ref>
</references>

[[Category:Comparisons]]

Differences between RAID-5- and RAID-6 - Revision history

Dwg: Article written and Venn diagram created.