Storage Parameters

Usable Capacity

12 TB

Fault Tolerance

Number of Drives

Capacity per Drive

Drive Type

RAID Level

Array Resilience

Architecture

RAID 5 • Parity

Fault Tolerance

1 Concurrent Failures Allowed

Current Configuration

RAID 5 (Parity)

12 TB Usable

Total RAW: 16 TB

Disk 01DATA

Disk 02DATA

Disk 03DATA

Disk 04PARITY

Total Drives

4 x 4 TB

Efficiency

75% Utilized

Usable: 12 TBWasted to redundancy: 4 TB

Pros & Cons

PRO: Good balance of capacity/speed/safety
PRO: Cost-effective redundancy
CON: Slower writes due to parity calculation
This setup prioritizes redundancy but has associated performance or capacity costs.

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RAID 6 Calculator

See dual-parity overhead and calculate RAID 6 usable capacity. A necessity for larger arrays and enterprise-class data protection.

How RAID 6 Capacity Is Calculated

Similar to RAID 5, RAID 6 distributes data stripes. But it creates a secondary parity block as well, meaning you lose two drives of capacity instead of one. The formula is: (Number of Drives - 2) × Size of Smallest Drive.

RAID 6 vs RAID 5

While RAID 5 gives you one more drive's worth of space, RAID 6 lets you suffer two total drive deaths simultaneously without losing a single file. And more importantly, if one drive fails, you still have parity protection while your array slowly rebuilds the replacement drive. See RAID 5 details.

When Dual Parity Is Worth It

Any time you construct an array of 6 or more drives, or use drives larger than 10TB, the probability of an Unrecoverable Read Error (URE) during array rebuild requires the safety net of dual-parity. See our full comparison for more or consider RAID 10 for performance.

RAID 6 FAQ

How much space do I lose in RAID 6?

You lose two drives worth of capacity. An array of 6x 10TB disks yields ~40TB of raw capacity (less after formatting).

Is RAID 6 slower than RAID 5?

Writing to a RAID 6 array is mathematically heavier due to the double parity calculation, resulting in somewhat lower write operations per second (IOPS), but read speeds remain excellent.