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 Capacity Guide

Raw Capacity vs Usable Capacity

When you purchase a 10 Terabyte drive, the manufacturer markets it using base-10 math (1 TB = 1,000,000,000,000 bytes). However, computers structure filesystems linearly in base-2 blocks (1 TiB = 1,099,511,627,776 bytes). Out of the gate, you lose approximately ~9% of your advertised capacity simply to computer formatting!

After this, the RAID overhead for RAID 5, RAID 6 or RAID 10 is subtracted, leaving your final usable storage.

Why the Smallest Drive Matters

Almost all standard RAID controllers build striped sets matching the smallest disk in the array. If you mix a 4TB drive with three 10TB drives in a RAID 5 array, the controller creates an array as if it were four 4TB drives, yielding only 12TB of space and completely wasting 18TB of real storage.

How Parity Affects Storage

Parity is error-correction math. Instead of cloning a file twice (RAID 1), parity uses logical XOR equations spanning multiple disks. If disk B crashes, the remaining disks A, C, and the Parity disk can reverse the equation to mathematically re-create the broken drive block by block.

Examples of RAID Capacity Calculations

8x 10TB drives in RAID 5: ~70TB Raw capacity (minus formating = ~63TB usable)
8x 10TB drives in RAID 6: ~60TB Raw capacity (minus formating = ~54TB usable)
8x 10TB drives in RAID 10: ~40TB Raw capacity (minus formating = ~36TB usable)