About

When designing enterprise storage infrastructure, the gap between raw capacity and usable space is often the first hurdle, but the disparity between theoretical and realized performance is where projects truly succeed or fail. This Advanced RAID Calculator is engineered for IT architects and system administrators who need more than just a capacity estimator.

Beyond standard storage efficiency, this tool computes theoretical IOPS (Input/Output Operations Per Second) based on specific drive technologies ranging from legacy 7.2k RPM spindles to modern NVMe arrays. It accounts for the inherent write penalties associated with parity-based RAID levels (like RAID 5 and 6), providing a realistic baseline for database throughput and file server responsiveness.

Formulas

The calculation of usable capacity and IOPS depends heavily on the chosen RAID level's parity and mirroring overhead. The formula for RAID 5 write performance, considering the parity penalty, is:

IOPS_write ≈ N × IOPS_drive4

Where N is the number of drives and 4 is the write penalty (2 reads + 2 writes per operation). For RAID 6, the penalty increases to 6.

Reference Data

Drive Type	Avg Random Read IOPS	Avg Random Write IOPS	Interface Limit (Approx)	Typical Use Case
HDD 7.2k RPM	80	80	150 MB/s	Cold Storage / Backup
HDD 10k RPM	130	130	200 MB/s	Legacy Database
HDD 15k RPM	180	180	250 MB/s	High-Perf Legacy
SSD SATA (Ent)	5,000+	4,500+	550 MB/s	Virtualization / Web
SSD SAS	10,000+	8,000+	1,200 MB/s	High-Traffic DB
NVMe Gen3	200,000+	150,000+	3,500 MB/s	AI / Big Data
NVMe Gen4	400,000+	300,000+	7,000 MB/s	Extreme Compute

Frequently Asked Questions

This is due to the 'Write Penalty'. Every write operation on RAID 5 requires reading the old data, reading the old parity, calculating new parity, and writing both new data and new parity. This results in 4 physical disk operations for every single logical write request.

No. This tool calculates raw theoretical disk performance. A high-quality hardware RAID controller with a battery-backed write cache (BBWC) can significantly absorb write penalties during bursts, masking the theoretical limits shown here.

NVMe performance varies wildly by model and workload depth. The values used here are conservative averages for enterprise-grade drives. In real-world scenarios, CPU bottlenecks or PCIe lane saturation often limit NVMe RAID speeds before the drives themselves hit their limit.

RAID 50 requires a minimum of 6 drives (two RAID 5 spans of 3 drives each). RAID 60 requires a minimum of 8 drives (two RAID 6 spans of 4 drives each). This tool validates your input against these constraints.