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How long does it take to rebuild a 16TB drive in a NAS?

In short · as of July 22, 2026

As a theoretical floor, a 16TB drive read or written flat-out at 180–260 MB/s sustained takes roughly 17–25 hours. Real rebuilds run longer — parity, concurrent use and throttling add time, and SMR can multiply it. At this capacity strongly prefer RAID 6 / SHR-2, and use CMR drives.

Last verified July 22, 2026 · 2 official sources checked Updated

Rebuild-time floor estimator
Theoretical floor: 22 h 13 m

This is a floor, not a promise: it assumes the drive reads or writes flat-out at the rate you set, with nothing else happening. Real rebuilds run longer — parity computation, using the NAS during the rebuild, and drive throttling all add time, and an SMR drive can multiply it. Sustained rates for current 3.5-inch NAS drives run roughly 180–280 MB/s (see each drive’s datasheet); 200 MB/s is a reasonable middle default.

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At 16 TB a rebuild is measured in the better part of a day or more, which is exactly why large arrays lean on double parity.

The theoretical floor

Capacity ÷ sustained transfer rate gives the fastest possible rebuild. Current 3.5-inch NAS drives publish sustained rates around 180–260 MB/s. A 16 TB drive: 16,000,000 MB ÷ (180–260 MB/s) ≈ 17–25 hours as a floor. Try your drive's rate in the estimator above.

Why real rebuilds run longer

Why it matters

A single-parity 16 TB rebuild leaves you unprotected for a day or more. At this capacity the case for RAID 6 / SHR-2 is strong — the rebuild is long enough that a second failure during it is a genuine risk, and double parity survives it. Use CMR drives and start the repair immediately. The table lists in-stock 16 TB CMR drives by price per terabyte.

16 TB CMR drives, by CA$/TB

Live Amazon.ca prices in CAD, ranked by price per terabyte. The Recording column is verified against manufacturer documentation.

Related questions

Sources

Every technical claim on this page is checked against manufacturer and standards documentation. Dates are when each source was last reviewed.