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RAID Array Capacity Formula:
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RAID (Redundant Array of Independent Disks) array capacity calculation determines the usable storage space in a RAID configuration after accounting for redundancy and parity data. Different RAID levels use different formulas to calculate usable capacity.
The calculator uses the standard RAID capacity formula:
Where:
Explanation: The formula calculates usable storage by subtracting the space used for parity from the total raw capacity, using the smallest disk size as the baseline for all calculations.
Details: Accurate capacity calculation is essential for storage planning, performance optimization, and ensuring adequate space for data protection and redundancy in RAID configurations.
Tips: Enter the smallest disk size in GB, total number of disks, and number of parity disks. All values must be positive numbers, and parity disks must be fewer than total disks.
Q1: What are common RAID levels and their parity requirements?
A: RAID 1: 1 parity disk per mirror; RAID 5: 1 parity disk; RAID 6: 2 parity disks; RAID 10: varies based on configuration.
Q2: Why use the smallest disk size for calculation?
A: In heterogeneous RAID arrays, all disks are limited to the size of the smallest disk to maintain consistency across the array.
Q3: How does RAID level affect capacity calculation?
A: Different RAID levels use different parity schemes, which affects how many disks are dedicated to redundancy versus usable storage.
Q4: What is the difference between raw capacity and usable capacity?
A: Raw capacity is the total of all disk sizes, while usable capacity is the space available for data after accounting for parity and redundancy.
Q5: Can I mix different disk sizes in a RAID array?
A: Yes, but the array will typically be limited to the size of the smallest disk for each disk's contribution to the total capacity.