RAID 5 maximises usable capacity with single parity; RAID 10 maximises write performance and rebuild speed with mirrors. Compare them on your drives in the RAID calculator (5 vs 10).
Capacity and cost
RAID 5 gives (n−1)/n usable — about 80% on five drives — so it's far more space-efficient than RAID 10's flat 50%. If capacity per pound is the priority and the workload is read-heavy, RAID 5 looks attractive on paper.
RAID 10 spends half your raw capacity on mirrors. You pay for that in drives, but you get it back in performance and rebuild safety. See the RAID 5 and RAID 10 calculators.
Performance and rebuilds
RAID 10 wins decisively on writes: a ×2 write penalty versus RAID 5's ×4, so roughly double the write IOPS. Its rebuilds are also fast and low-impact — a straight copy from the surviving mirror — whereas RAID 5 must read every surviving drive and recompute parity, which is slow and, on large drives, risky.
That rebuild risk is the clincher: during a RAID 5 rebuild there's no redundancy left, so a read error means data loss (see is RAID 5 dead?). RAID 10 keeps the other mirrors intact.
Which to choose
Choose RAID 5 for smaller arrays of modest or solid-state drives, read-heavy workloads, and where capacity efficiency matters and you have a backup. Choose RAID 10 for write-heavy databases, busy virtualisation, and anywhere rebuild speed and predictable latency matter.
On large nearline HDDs, prefer RAID 6 over RAID 5 for rebuild safety, or RAID 10 if writes dominate. The calculator's compare mode makes the trade-off concrete.