NAS hard drives

Drives rated to run continuously in a multi-bay enclosure, and what that rating actually covers.

A NAS drive differs from a desktop one in firmware and rated duty rather than in the platters: it is built to run every hour of the year alongside other drives, with vibration tolerance and error recovery timings suited to a RAID array. Those are the specifications worth checking here, and they are the ones a desktop drive quietly lacks.

What an ordinary nas drive looks like

Medians, with values beyond 1.5× the interquartile range excluded so one listing cannot move them. A class holding fewer than 8 drives publishes no baseline at all.

How this class is distributed

54 drives in this corpus sit in this class. By capacity:

What the continuous rating actually buys

The phrase that matters on a NAS listing is the rated workload, usually given in terabytes written and read per year. A desktop drive is typically rated for a fraction of what a NAS drive is, and that difference is not about build quality so much as about what the manufacturer will stand behind. A drive run past its rated workload does not fail on a schedule; it simply leaves the envelope the warranty describes, which is a commercial fact rather than a mechanical one. It is also the reason NAS drives carry longer warranties than desktop drives here, and the reason the price gap between the two is smaller than the gap in what they are rated to do.

Vibration is the specification nobody reads

A drive alone on a desk sits still. A drive in a four-bay enclosure sits in a box with three other spinning masses, and the rotational vibration they generate makes the heads work harder to stay on track. NAS drives carry sensors and firmware to compensate; desktop drives generally do not, which is why a desktop drive in a busy array can post read speeds well below its rating without anything being wrong with it. This matters more as bays increase, and barely at all in a two-bay box.

Error recovery is the difference that breaks arrays

When a desktop drive hits a bad sector it will retry for a long time — sometimes minutes — because on a single-drive machine the data is worth waiting for. A RAID controller has no such patience: a drive that stops answering for that long is treated as failed and dropped from the array. NAS drives cap their retry time so the controller can handle the error instead. This is the single most common reason a working desktop drive gets ejected from an array, and it is a firmware setting rather than a defect.

Where the class sits in this corpus

NAS drives here cluster among the larger capacities and carry the biggest caches, alongside enterprise drives. They are not the cheapest per terabyte in the corpus — enterprise drives are, because they are sold larger still — but they are substantially cheaper per terabyte than desktop or laptop drives, which is the opposite of what their positioning suggests. If the requirement is bulk storage that runs continuously, the premium over a desktop drive is smaller than it looks once it is measured per terabyte rather than per drive.

Shingled recording, and the word that is missing

Drives record in one of two ways. Conventional recording writes tracks side by side; shingled recording overlaps them like roof tiles to fit more on a platter, which makes rewriting a track require rewriting its neighbours. On sustained writes a shingled drive can slow to a fraction of its rated speed once its cache fills, and in a RAID rebuild that can turn hours into days. The tell is what listings choose to say: in this corpus the term CMR appears roughly twenty times more often than SMR, because conventional recording is advertised as a feature and shingled recording is simply not mentioned. Silence is not evidence of either, but a drive that makes a point of saying CMR is telling you something a drive that says nothing is not.

Recertified and renewed listings

Roughly one listing in seven here is sold as recertified, renewed or manufacturer-refurbished. These are drives that have been returned or pulled from service, tested and resold, and they are usually the cheapest per terabyte on the page. What changes is the warranty — often months rather than years — and what is not disclosed is the hours already on the drive. For storage where the data exists elsewhere, the arithmetic can be sound. For the only copy of anything, buying a drive with an unknown history to save a fraction of its price is a poor trade, and the price per terabyte on this page does not distinguish between the two.

Why the capacity you get is smaller than the one you bought

Drive manufacturers count a terabyte as a trillion bytes; operating systems generally count it as 2^40, about ten per cent more. A 4 TB drive therefore shows as roughly 3.63 TB before a single file is written, and nothing is wrong. Formatting and the file system take a further small share. This is not a specification any listing states and it is the most common reason a new drive appears to have arrived short, so it is worth expecting rather than discovering.

RAID is not a backup

An array survives a drive failing. It does not survive a deleted file, a corrupted one, ransomware, a failed controller, a power event that takes two drives at once, or the building it sits in. Every one of those propagates across the array immediately and by design, because the array’s job is to keep the copies identical. A NAS is a convenience and a redundancy measure, and it becomes a backup only when something copies its contents somewhere it cannot reach. The drives on this page are the right ones for continuous operation; none of them changes that.

Reading these figures

Every number above is a median of what manufacturers publish, not a measurement we took. Where a specification is missing from this table it is because too few listings in the class stated it for a median to mean anything — that is a fact about the listings, not about the drives.

Narrow this class by capacity and budget in the hard drive finder.

Computed from the corpus on 2026-08-29.