Work out disk iops from spindles instantly with clear inputs, formula shown and shareable results.
Each host write becomes several back-end operations under parity RAID: RAID 5 needs two reads and two writes, giving a penalty of 4, and RAID 6 a penalty of 6. Front-end IOPS is therefore raw IOPS divided by the read-weighted average penalty, which is why a write-heavy workload on RAID 6 delivers a fraction of the array's nominal capability.
RAID IOPS
raw = disks x per-disk IOPS; effective = raw / (read share + write share x write penalty)
A partial-stripe write reads the old data and old parity, then writes the new data and new parity — four operations for one logical write.
The RAID arithmetic is identical, but their IOPS ceiling is so much higher that the penalty rarely binds. SSD write amplification and endurance become the concern instead.