RAID Calculator

A RAID array trades part of its raw capacity for redundancy, and how much depends on the level. Enter the number of drives, the capacity of one drive and the RAID level, and it returns the usable space in both decimal and binary units, the capacity given up to parity or mirroring, and how many drives can fail. A second tab lays all five levels side by side for the same set of drives. It covers RAID 0, 1, 5, 6 and 10 only, and stops at capacity, so rebuild time, rebuild risk and controller behaviour are not modelled.

Calculator Type
Capacity Unit

Usable space, parity or mirror overhead and fault tolerance for a set of identical drives.

If the drives are not all the same, enter the smallest one. An array levels every member down to it.
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Capacity Unit

The same drives arranged five ways, so the trade between space and redundancy is visible at once.

If the drives are not all the same, enter the smallest one. An array levels every member down to it.
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