1. What is RAID Capacity Calculation?

RAID (Redundant Array of Independent Disks) capacity calculation determines the usable storage space in a RAID array after accounting for redundancy and parity overhead.

2. How Does the Calculator Work?

The calculator uses the RAID capacity formula:

Where:

• \( \min(disk\ sizes) \) — The smallest disk size in the array
• \( n \) — Total number of disks in the array
• \( p \) — Number of parity disks

Explanation: The formula calculates usable capacity based on the smallest disk size (which determines the stripe size) and subtracts the parity overhead.

3. Importance of RAID Capacity Planning

Details: Proper RAID capacity planning is essential for storage optimization, performance tuning, and ensuring adequate space for data protection and redundancy.

4. Using the Calculator

Tips: Enter disk sizes as comma-separated values (e.g., "1000, 2000, 1000, 2000"), specify the number of parity disks, and click calculate.

5. Frequently Asked Questions (FAQ)

Q1: Why use the smallest disk size in calculation?
A: RAID arrays are limited by the smallest disk because data is striped across all disks, and each stripe segment must be the same size.

Q2: How does parity affect capacity?
A: Parity disks store redundancy information, reducing usable capacity but providing fault tolerance. More parity disks mean less usable space but better protection.

Q3: What RAID levels use this formula?
A: This formula applies to RAID 5 (1 parity disk), RAID 6 (2 parity disks), and similar parity-based RAID configurations.

Q4: Can I mix different disk sizes in RAID?
A: Yes, but the array will use the smallest disk size as the effective size for all disks, potentially wasting capacity on larger drives.

Q5: What about RAID 0 and RAID 1 capacity?
A: RAID 0 capacity = sum of all disk sizes, RAID 1 capacity = size of one disk (mirrored). This calculator focuses on parity-based RAID configurations.