What is the RAID Storage Calculator?
The RAID (Redundant Array of Independent Disks) Calculator is an IT infrastructure tool. It calculates the total usable storage capacity, fault tolerance, and read/write performance gains when combining multiple physical hard drives into a single logical volume using different RAID levels (like RAID 0, 1, 5, or 10).
How to Calculate Usable RAID Capacity (Formulas)
The usable space entirely depends on the mathematical parity or mirroring required by the specific RAID level.
- RAID 0 (Striping): Total Capacity = Sum of all drives. (Zero redundancy).
- RAID 1 (Mirroring): Total Capacity = Capacity of one drive. (Exact clone).
- RAID 5 (Parity): Total Capacity = (Number of Drives - 1) * Capacity of the smallest drive.
- RAID 10 (Stripe of Mirrors): Total Capacity = (Number of Drives * Capacity) / 2.
Frequently Asked Questions
What happens if a drive fails in RAID 0?
RAID 0 offers incredible read/write speeds by splitting data across all drives simultaneously, but it has zero fault tolerance. If a single drive in a 4-disk RAID 0 array fails, the entire array collapses, and 100% of the data on all four drives is permanently destroyed.
Why does RAID 5 "lose" the capacity of one drive?
RAID 5 distributes "parity data" mathematically across all drives in the array. This parity acts as an algebraic checksum. If any single drive physically dies, the system uses the parity data remaining on the surviving drives to mathematically rebuild the lost data. This protection costs exactly the equivalent capacity of one hard drive.
Is RAID a replacement for backups?
RAID IS NOT A BACKUP. RAID only protects against hardware drive failure, allowing a server to stay online while you hot-swap a broken disk. It does absolutely nothing to protect against ransomware, accidental file deletion, corrupted software, or the server room catching fire. You still need an offsite backup.