1 · Choose a RAID level
Striped mirrors. Guaranteed one failure; up to one per mirror pair if losses do not collide.
2 · Configure drives
3 · Drive class
12G SAS SSD — indicative figures.
Advanced — read/write mix, URE rate
Calculated for planning. We don't publish prices — a 24-year UK reseller, Servnet confirms the exact drives, array and pricing on quote. IOPS, throughput & rebuild are indicative estimates.
What RAID 10 is
RAID 10 stripes data across mirrored pairs, combining RAID 1 redundancy with RAID 0 striping. Usable capacity is half the raw (n/2 × drive size) and it delivers the best write performance of the resilient levels thanks to a ×2 write penalty.
It always survives one failure and can survive up to one drive per mirror pair if losses do not collide. Rebuilds are fast — just a copy from the surviving mirror, not a parity recalculation across the whole array — which is why RAID 10 is the standard for write-heavy, latency-sensitive databases despite its 50% efficiency.
Eight 8 TB SSDs in RAID 10 give 32 TB usable and the highest write IOPS of any resilient level — each host write costs only two back-end I/Os. The price is 50% efficiency: 64 TB raw for 32 TB usable.
Advantages
- Best write performance of the resilient levels (×2 penalty)
- Fast, low-impact rebuilds (mirror copy)
- Excellent random I/O for databases / VMs
- No parity-calculation overhead
Trade-offs
- Only 50% capacity efficiency
- Guaranteed to survive just one failure (more only if lucky)
- Expensive per usable TB
- Needs an even number of drives
Best for
- Write-heavy transactional databases (SQL, Oracle)
- Latency-sensitive virtualisation / VDI
- Mixed random I/O workloads
- Anywhere rebuild speed is critical
Consider another level when
- Capacity-led bulk / archive storage
- Budget-constrained capacity needs
- Read-mostly workloads where RAID 6 is cheaper
RAID 10 — common questions
How much usable capacity does RAID 10 give?
Half the raw capacity — n/2 × drive size. Eight 8 TB drives give 32 TB usable (50% efficiency), because every drive is mirrored.
How many drives can RAID 10 lose?
It always survives one failure. It can survive more — up to one drive per mirror pair — but only if no two failures land in the same pair. The guaranteed (worst-case) figure is one drive, which is what the calculator reports.
Why is RAID 10 better for databases?
Its ×2 write penalty (versus ×4 for RAID 5 and ×6 for RAID 6) means far higher write IOPS, and rebuilds are a fast mirror copy rather than an array-wide parity recalculation — both of which matter for write-heavy, latency-sensitive databases.