Calculate usable capacity of a RAID 10 striped-mirror array from disk count and size.
RAID 10 combines mirroring (RAID 1) and striping (RAID 0) by creating mirrored pairs of disks, then striping data across those pairs. Usable capacity is exactly half the raw capacity. It offers both good random I/O performance (from striping) and redundancy (from mirroring), tolerating one disk failure per mirror pair without data loss.
RAID 10 usable capacity
usable = (n / 2) × disk_size
RAID 10 mirrors disks in pairs before striping across pairs, so each disk needs a partner — an odd number leaves one disk without a mirror, which most controllers do not allow.
For random writes, yes — RAID 10 has no parity calculation overhead, so write latency is lower. Read performance is comparable or slightly better due to mirror read splitting.