RAID 60 calculator

Striped RAID 6 groups — dual parity per group for very large pools. Set your drives below and this RAID 60 calculator returns live usable capacity, fault tolerance, IOPS, rebuild time and URE risk.

1 · Choose a RAID level

Stripe & mirror

Single parity

Dual / triple parity

Nested

ZFS RAID-Z

Striped RAID 6 groups. Two failures per group.

2 · Configure drives

RAID groups

Drives / group

Capacity per drive (TB)

3 · Drive class

3.5" nearline SAS/SATA capacity HDD — indicative figures.

Advanced — read/write mix, URE rate

Workload mix: 70% read / 30% writeDrive URE rate

RAID 60 · 12 × 16 TB

128 TB usable

of 192 TB raw · 66.67% efficiency

Fault tolerance2 per RAID-6 group (up to 4); a 3rd loss in any one group is fatal

Write penalty×6

IOPS estR ≈1K · W ≈240 · mix ≈576

Throughput estR ≈2K · W ≈2K MB/s

Rebuild / drive est≈ 55.6 h

URE on rebuild recoverable47.2%

With redundancy still remaining during a single-drive rebuild, a URE here is reconstructed (recoverable) — not data loss. Data loss requires a concurrent second failure. Figure shown is the chance of encountering a URE.

Calculated for planning. We don't publish prices — a 20+ year UK reseller, Servnet confirms the exact drives, array and pricing on quote. IOPS, throughput & rebuild are indicative estimates.

Overview

What RAID 60 is

RAID 60 stripes data across multiple RAID 6 groups, each with dual parity. Usable capacity is groups × (drives-per-group − 2) × drive size, and every group survives two failures — so the array tolerates two losses per group and rebuilds them independently.

It is the most resilient mainstream level for very large arrays of high-capacity drives: even mid-rebuild, each group retains parity to cover a URE, and a wide pool is split into smaller, faster-rebuilding groups. The trade-off is capacity (two parity drives per group) and a ×6 write penalty.

At a glance

Usable capacitygroups × (per-group − 2) × drive size

Minimum drives8

Fault tolerance2 per RAID-6 group

Write penalty×6

Worked example

2 groups × 6 × 16 TB nearline → 128 TB usable, 2 failures per group

Two RAID 6 groups of six 16 TB drives give 128 TB usable and tolerate two failures in each group. It is the resilient choice for big capacity pools — each group rebuilds independently and survives a URE mid-rebuild.

Advantages

Survives two failures per RAID 6 group
URE during rebuild is recoverable per group
Shorter rebuilds than one very wide RAID 6
Ideal for very large capacity pools

Trade-offs

Two parity drives per group — lower efficiency
×6 write penalty
Needs at least 8 drives
More planning (group sizing)

Best for

Very large nearline / capacity arrays
Archive, media and backup repositories at scale
Maximum resilience without going all-flash

Consider another level when

Write-heavy databases
Small or mid-size arrays
Latency-critical workloads

Compare other levels

RAID 6 →RAID 50 →RAID 10 →RAID 0 →RAID 1 →RAID 5 →RAIDZ1 →RAIDZ2 →RAIDZ3 →RAID 1E →RAID 4 →RAID 5E →RAID-DP →RAID-TEC →All levels →

RAID 60 — common questions

How is RAID 60 capacity calculated?

Usable capacity is groups × (drives-per-group − 2) × drive size. Two groups of six 16 TB drives give 2 × (6−2) × 16 = 128 TB usable.

How resilient is RAID 60?

Each RAID 6 group survives two failures, so a two-group array can lose up to four drives if they are spread two-per-group. Even during a single-drive rebuild, each group keeps a parity to cover a URE — making it very safe for large drives.

When should I choose RAID 60 over RAID 6?

On very large arrays where one wide RAID 6 would rebuild too slowly, RAID 60 splits the pool into smaller groups that rebuild faster and independently, while keeping dual-parity protection in each group.