Dahua recorders — NVR, XVR and IVSS
The recorder is the heart of the system: it decides how many cameras fit, how long footage is kept, how quickly you can find something and how much analytics runs at all. The same camera behind two different recorders gives you two quite different systems.
Related pages: camera model codes
and series · technologies (WizSense, AcuPick, SMD) ·
software (Smart PSS Lite, DSS). This page is only about the
hardware recorder.
1. Three kinds of recorder
| Type | What it records | For whom |
|---|---|---|
| NVR | IP cameras only, over the network. Many models have their own PoE ports, so cameras connect straight to the recorder. | The default choice for any new site. |
| XVR | "Penta-brid", 5-in-1: HDCVI, AHD, TVI, CVBS and IP in the same device, with automatic signal detection. | Where coaxial cable already exists or an old analogue system is being upgraded gradually. |
| IVSS / EVS | Server-class machine: hundreds of channels, a RAID array, redundant power, serious AI hardware. | Large and critical sites where losing data is not an option. |
The most common mistake: choosing a recorder by channel
count alone. Channel count is the least limiting figure — bandwidth (Mbps),
storage and AI channels run out first.
2. The model code decoded
NVR — IP recorder
NVR5series2drive bays16channels-16PPoE ports-EIAI support
| Part | Meaning |
|---|---|
NVR | Network Video Recorder — IP cameras only. |
| 1st digit | Series — see below. |
| 2nd digit | Number of drive bays: 1, 2, 4 or 8. On larger
machines 08 = 8 bays, 16 = 16 bays. |
| 3rd–4th digit | Channel count: 04, 08, 16, 32, 64, 128. |
HS | Compact 1U chassis. H = drawer chassis on large
machines. |
16P, 8P, 4P | Number of built-in PoE ports. Without them, cameras need a separate PoE switch. |
4K, 4KS2, S3 | Resolution class and hardware generation. |
I, EI, XI | AI support.
Without one of these the recorder has no analytics. XI marks the AI NVR
line — the most capable. |
/L | Lite version, reduced capability. |
XVR — analogue plus IP
XVR5series1drive bays08channelsHSchassis-4KLresolution-I3AI generation
On an XVR the series digit indicates the AI platform: 4, 5 and 7 = WizSense,
8 = WizMind. The trailing -I, -I2, -I3
marks the AI generation, and 4KL means the 4K-Lite class. Here
4P/8P denotes PoC ports — power and video over one
coaxial cable.
IVSS and EVS — server class
Here the code tells you the size of the machine: IVSS7124DR-8I = series 7,
24 drive bays, D = LCD screen on the front panel,
R = redundant power supply, 8I = 8 AI modules.
On an EVS, S marks a single controller and D a dual controller, with
R again meaning redundant power.
3. NVR series — what actually differs
| Series | Character | When to choose |
|---|---|---|
| 2 | Lite. Few channels, one drive, modest bandwidth. | Home and small sites with a handful of cameras. |
| 4 | The workhorse. Usually 1–2 drives, often built-in PoE, WizSense AI. | The default for most sites — flats, houses, offices, shops, warehouses. |
| 5 | Pro. More bandwidth, more drives, often two network ports and N+M clustering, eSATA expansion. | Dozens of cameras, several monitors, a system that must run for years. |
| 6 and XI | Ultra / AI NVR. Many drive bays, up to 128 channels, serious AI hardware. | Large sites. Order item — not normally held in stock. |
RAID depends on the number of drive bays, not the series.
Small 1–2 bay desktop models have no RAID — the drives sit in a disk group, where each
drive records its own cameras and one failed drive takes that drive's footage with it. RAID
starts with the larger chassis: the NVR5832-EI, for example (32 channels, 2U,
8 drive bays), supports
RAID 0/1/5/6/10, as do the series 6 and server-class
machines. So RAID is available within series 5 too — but only from the 8-bay model
upwards.4. How the recorder and camera work together — the AI split
This is the single most important thing to understand when choosing a recorder. Dahua splits analytics in two, and each side has its own limits. Example from the datasheet of the NVR5216-EI we stock:
| AI by Recorder the recorder computes |
AI by Camera the camera computes, the recorder receives | |
|---|---|---|
| What it can do | Face detection and recognition, perimeter protection, SMD Plus | Face detection and recognition, perimeter protection, SMD Plus, video metadata, ANPR, stereo analysis, heat map, people counting |
| On how many channels | Limited: 2 channels of face detection, 4 channels of perimeter protection, 8 channels of SMD Plus | Every camera that has it — the recorder is not the bottleneck |
| What camera it needs | Any camera, including old ones or other brands | A camera with AI — see camera series |
The practical conclusion: if you want analytics on
every camera, buy it in the camera, not in the recorder. The
recorder's own AI is meant to cover a few important channels and to rescue older cameras. On a
32-channel site no recorder covers every channel by itself.
What this means per camera series
| Camera | What actually runs |
|---|---|
| Series 1 (Entry) | The camera does no analytics itself. The recorder can give it SMD Plus or perimeter protection — but only on as many channels as the recorder can manage. |
| Series 2 and 3 (WizSense) | People/vehicle classification and perimeter protection come from the camera, so they run on every camera at once. This is the right answer for an ordinary site. |
| Series 5 (WizMind) | Adds face recognition, ANPR, counting and video metadata — these arrive at the recorder ready-made. The recorder only has to receive them and make them searchable. |
AcuPick is the exception: it works as
camera and recorder together and needs support from both. Then hours of footage can be
searched for a person or vehicle in one click. See the
technologies page.
5. Hard drives
Surveillance drives are not ordinary computer drives. A recorder writes around the clock, for years, from several streams at once — a desktop drive is not designed for that and wears out quickly.
| Drive | What it is for |
|---|---|
| Seagate SkyHawk / WD Purple | Surveillance drives: continuous writing, vibration tolerance, several simultaneous streams. |
| SkyHawk AI | The same, but built for higher channel counts and the random read load of AI systems. For large installations. |
| Desktop drive | Not suitable. It works at first, but wears out early and usually fails exactly when the footage is needed. |
How much capacity? Rule of thumb: add up the cameras'
bitrates (Mbps) and multiply by the days you want to keep. 16 cameras at 4 Mbps is 64 Mbps, or
roughly 690 GB per day — about 20 TB for 30 days. Motion-based recording and Dahua's
AI Coding, which can halve the bitrate, reduce that noticeably. Just ask —
we will work it out with you.
6. Data resilience — RAID, redundancy and backup
RAID
RAID combines drives into one array so that one (or two) failed drives do not take the data with them. Where you can have it:
| Machine | Drives | RAID |
|---|---|---|
| Compact desktop model (e.g. NVR4216-EI) | 1–2 bays | No — disk group only |
| 2U machine (e.g. NVR5832-EI) | 8 bays | RAID 0/1/5/6/10 |
| Series 6 and AI NVR | 8–16 bays | Yes |
| IVSS / EVS (e.g. IVSS7124DR-8I) | up to 24 bays | RAID 0/1/5/6/10/50/60 plus a redundant power supply |
RAID is not a backup. RAID protects against a
drive failure. It does not help if the device is stolen, burns, is wiped by a command,
or if someone deliberately clears the recorder. A critical site needs real backup as well.
Before writing RAID into a specification — what it costs.
We see this often: a simple site with four or five cameras carries a RAID requirement in its
technical specification. The consequence is that a compliant recorder is no longer a small
desktop unit but an 8-bay 2U machine — and RAID 5 needs
at least three drives, RAID 6 four. On a four-camera site that can multiply the
cost of the recording solution without the customer's actual protection rising in proportion.
Often the real risk lies elsewhere — the device being stolen or wiped, which RAID does not address at all. On a small site, ANR (the camera's memory card covering network outages) and a copy of the footage in a second location buy more for the same money.
If the requirement is already written down, it is worth asking whether it is a genuine availability requirement or carried-over text. Ask us — we will price both options so you can compare.
Often the real risk lies elsewhere — the device being stolen or wiped, which RAID does not address at all. On a small site, ANR (the camera's memory card covering network outages) and a copy of the footage in a second location buy more for the same money.
If the requirement is already written down, it is worth asking whether it is a genuine availability requirement or carried-over text. Ask us — we will price both options so you can compare.
Backup and resilience options
| Option | What it gives you |
|---|---|
| Export to USB or network | The standard way to take out a specific clip — for the police or an insurer. Available even on an ordinary NVR. |
| eSATA | An external drive enclosure for extra capacity or archiving (on larger models). |
| ANR — automatic network replenishment | During a network outage the camera records to its own memory card and transfers the footage to the recorder once the link is back. The gap in the recording disappears. The only requirement is that a card is actually fitted — the slot itself is present on almost every Dahua camera except series 1. The card has to be bought and installed separately, which is often forgotten, and then ANR does not work. |
| N+M cluster | A standby recorder: if one fails, another takes over its cameras. Supported from series 5 upwards. |
| Two network ports | Load balancing or failover — the camera network and the office network can also be physically separated. |
| A second location | The strongest protection: important footage is copied elsewhere, for example to a DSS server. |
7. When you need an IVSS or a server
A server-class machine is not "a bigger NVR" — it solves different problems. The IVSS7124DR-8I we stock shows where the line runs: up to 256 IP channels, 768 Mbps incoming and recording, up to 128 channels of face recognition and video metadata at once, up to 500,000 faces in the database, 24 drive bays with RAID and redundant power.
Three signs an ordinary NVR will not do: (1) more than a
hundred cameras, or bandwidth beyond a couple of hundred Mbps; (2) analytics needed on dozens of
channels at once rather than a few; (3) the system must not stop even when a drive or a power
supply fails.
We do not normally stock IVSS, EVS and the large NVRs — they are ordered
for a specific project. Videovalve is the official Dahua importer, so
ask for a quote and describe the site.
8. Where the recorder ends and DSS begins
The recorder records. Once sites are added or there are more than a couple of users, what runs short is management — and that is where a software platform belongs.
| Situation | What you need |
|---|---|
| One site, one or two viewers | A recorder plus Smart PSS Lite. Nothing more is needed. |
| Several sites or several operators | The recorders stay, but DSS Express goes on top — central user management, a shared event feed, all sites in one view. |
| A large system with analytics and reporting | DSS Professional: face databases, ANPR reports, map view, integrations. |
Important: DSS does not replace the recorder. The usual
design is recorders on site (recording happens locally and keeps working even if the link drops)
with DSS above them as the management and viewing layer. See the
software page.
Sources: Dahua's official model naming rules "Name Rule V20231012" (NVR, AI NVR, XVR, IVSS, EVS) · Dahua datasheet DHI-NVR5216-EI (AI by Recorder / AI by Camera channel counts, N+M cluster, backup methods) · product datasheets in the Videovalve catalogue. Exact figures vary by model — always check the datasheet of the specific product or ask us.