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RAID 60 calculator

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

DataDistributed parity

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

3 · Drive class

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

Advanced — read/write mix, 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 risk47.2%

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.

Capacity distribution66.67% usableUsable: 128 TB128Parity: 64 TB64Usable · 128 TBParity · 64 TB
Fault tolerance — parity per groupgroup 1DDDDPPgroup 2DDDDPPDataParity2 per RAID-6 group (up to 4); a 3rd loss in any one group is fatal
IOPS — back-end budget vs deliveredBack-end budget1KFront-end read1KFront-end write240Write penalty ×6 — each host write costs 6 back-end I/Os
URE risk during a single-drive rebuild0%25%50%75%100%47%data read during rebuild (307.2 TB →)URE 1 in 10^15

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.

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
Level landscape — efficiency vs fault tolerance (typical)012325%50%75%100%drives survivedspace efficiency →RAID 0RAID 5RAID 50RAID-Z1RAID 6RAID 60RAID-Z2RAID-Z3RAID 10RAID 1

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.