NVR Recorders - and the Drive That Finishes the Job

NVR or NAS: the honest comparison

A network video recorder is a small appliance that does one job: take RTSP streams from IP cameras, write them to a disk, and let you scrub back through them. A NAS running surveillance software does the same job as one application among many, on hardware you probably already own.

The case for the NVR is that it is finished. It arrives configured for the job, it usually has a built-in PoE switch so the cameras get power and network over one cable each, and the person setting it up does not need to know what a container is. For most households that is worth more than flexibility, and the PoE switch alone is a meaningful part of the price difference.

The case for the NAS is that you already have one, that surveillance is one workload among several rather than a dedicated box, and that the storage is managed by a filesystem you trust with redundancy you chose. It is also the only route if you want the footage to live on the same array as everything else and be backed up by the same process.

The honest verdict is that this is not a close-run technical argument, it is a question about what you already own and what you want to maintain. If there is no NAS, an NVR is cheaper and finished. If there is a NAS with spare bays and spare CPU, the marginal cost of surveillance software on it is close to nothing, and the camera licence model of some NAS vendors is the thing to check before assuming that.

One genuine technical difference worth knowing: NVRs with a built-in PoE switch usually put the cameras on their own isolated network segment. That is a real security benefit - IP cameras are not famous for their firmware quality, and keeping them off the main network is a defensible reason to prefer the appliance regardless of the storage argument.

Diskless or bundled, and why we make the distinction loudly

Recorders in this category ship in three states and the listings are not consistent about saying which. Some are diskless: the box arrives empty and records nothing until you fit a drive. Some come with a drive already inside. And a substantial number simply do not say, which is the state the table above renders in amber.

That third state is the expensive one. A buyer who assumes a drive is included and finds an empty box has a recorder that cannot record, on the day they installed the cameras. A buyer who assumes it is diskless and buys a drive has spent money twice. Neither is a disaster and both are annoying, and the fix is to check the specific listing rather than the category.

For our purposes the diskless case is the interesting one, because it is where a storage site can actually help. A diskless recorder plus the right drive is a complete purchase, and the basket below prices it as one - the recorder and a surveillance-class drive at our current tracked prices.

We price ONE drive in that basket, deliberately. Consumer recorders in this class overwhelmingly take one or two 3.5-inch bays regardless of channel count, and we do not hold a sourced bay count for each model - the seeding session captured channel counts, not chassis specifications. Multiplying by a bay count we would be guessing at is exactly the kind of inference this site does not publish, so the basket prices one drive and says so.

Why a surveillance drive and not the cheapest one

This is the part where the storage argument is real rather than marketing, and it is worth being precise about what the difference actually is.

A desktop hard drive is designed around an assumption: that it is mostly idle, that work arrives in bursts, and that reads and writes are mixed. A surveillance recorder violates every part of that. It writes continuously, from many streams at once, forever, and it almost never reads. Eight cameras recording around the clock is eight simultaneous sequential write streams into one disk, twenty-four hours a day, for years.

Surveillance-class drives - Seagate's SkyHawk line and Western Digital's Purple line are the two you will meet - are specified for that duty and their makers publish a workload rating in terabytes written per year to describe it. Our capacity pages carry those ratings per part number rather than blanketed across a tier, because they differ within a family.

There is a second, less discussed difference: error recovery timing. A desktop drive that hits a bad sector may spend a long time trying to recover it, during which it is not accepting writes. In a recorder, that means dropped frames from every camera. Surveillance and NAS-class drives limit how long they will spend on a recovery attempt for exactly this reason.

None of that means a desktop drive will fail immediately in a recorder. It means the duty cycle it is being asked for is outside what its maker specified, and that the failure - when it comes - arrives without warning in a box nobody looks at until they need the footage.

Sizing the drive, without a bitrate we have not sourced

The question everybody asks is how many terabytes for how many cameras for how many days, and the honest answer is that it depends almost entirely on a number we are not going to invent for you: the bitrate each camera is actually recording at.

That figure varies by more than an order of magnitude across otherwise similar cameras, driven by resolution, frame rate, codec, and whether the camera is looking at a still car park or a windy tree. The same 4K camera can produce a small fraction of the data on H.265 with motion-triggered recording that it produces on H.264 recording continuously. Publishing a terabytes-per-camera-per-day figure would be publishing an average of things that are not alike.

What we will give you is the arithmetic and the instruction to fill in your own number. Total bitrate across all cameras, in megabits per second, times the seconds in your retention period, divided by eight for bytes, is the storage you need. Your camera or your recorder reports its actual stream bitrate - most NVR interfaces show it live, per channel - and that measured number beats any published estimate.

The capacity ladder attached to each channel-count page below is ours and is labelled as ours: it is a floor we are willing to put in front of a channel count, not a retention calculation. More cameras means more simultaneous streams means more bytes per day at the same retention, which is why the floor rises with channels. It is a starting point for a basket, not an answer to your retention question.

One practical note that overrides all of the above: recording continuously at full frame rate is rarely what people actually want. Motion-triggered recording, or continuous recording at a reduced frame rate with full rate on motion, cuts the storage requirement dramatically and is what most of these recorders do by default.

What we are not claiming about any of this hardware

There are no performance claims on this page. We do not test recorders, we have not measured how many streams any of these boxes can actually handle simultaneously at their advertised resolution, and we are not going to repeat the seller's channel count as though it were a measurement of sustained capability.

Channel count is what the listing states and it is in its own column labelled as such. It describes how many cameras the recorder will accept, which is not the same claim as how many it will record at full resolution and full frame rate without dropping anything.

We also publish no camera recommendations. This is a storage site; the cameras are somebody else's subject, and the surveillance camera-kit market is full of rebadged hardware where the brand on the box tells you very little about who made what is inside it. Our brand gate for this category rejected a meaningful number of listings on exactly that basis, and we would rather cover the storage question properly than the camera question badly.

Where to go next

8-channel recorders · 16-channel recorders · Seagate SkyHawk and WD drive families are the surveillance-class options · NAS devices if the answer is a NAS running surveillance software instead · SATA drives by capacity · Drive lifespan - a recorder is the hardest continuous duty most consumer drives ever see · add power protection, since a recorder that reboots mid-write loses the footage it was taking.

Frequently asked questions