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DVR’s vs. Server Systems

How is a Server-Based System Better Than a System That Uses Digital Video Recorders?

Digital video recorders are simply PCs in a box. They generally run Windows or Linux operating systems and they are equipped with a circuit board that allows you to connect typically up to sixteen video cameras to them. They generally have a number of features as part of their feature set including motion detection and they output images in sixteen matrix format onto a monitor. So in this regard they are computers with camera inputs, an internal multiplexer and a monitor output.

Typically DVRs can be purchased with up to 1TB of hard drive storage and some better product lines allow you to add an external drive for storage but at a premium cost. You can network DVRs together with a separate PC that runs special software that allows the operator to control the images.

Images from the sixteen cameras connected to a specific DVR are recorded on that DVR or its external drive unit. When a DVR’s drive capacity is filled, older data is over written by newer data. It does not have the ability to send its data to another DVR’s drive with spare capacity.

Server-based systems replace the DVRs with a server. The server is equipped with a rack of hard drives in a RAID configuration. Better systems like the Acuity-vct use a better server. Because they run only one copy of their operating system and not one copy per DVR they are more efficient and less prone to problems. Most DVR systems must run the operating system designated by the manufacturer, generally Windows, but better server based systems like Acuity-vct can run operating systems like Linux which are more desirable to many IT managers.

Because they are more powerful and faster, server-based systems can do more. They can also be expanded when you want more cameras. When a DVR is fully configured with its sixteen cameras, you need to buy a new $8000 DVR just for a seventeenth camera but with a server-based system you don’t have such limitations. The Acuity-vct system is so powerful that you can add 1000 cameras to the system if you want. Data is written to whatever part of the drive array has spare capacity, not to a specific drive.

Similarly, a DVR can display only 16 images on a monitor but a server-based system like Acuity-vct lets you put as many images on a monitor as you want. You can buy larger monitors and display more images, further reducing the cost of the system. You can use larger monitors with DVRs, of course. But because you are limited to sixteen images per monitor this can be costly. And who has the space in their control room for this anyway?

As digital cameras with higher megapixel resolution become more affordable you will want the ability to show pictures in full screen mode on very large monitors to see detail. This would be cost prohibitive with a DVR system of any size.

If your CCTV system has only 16 or fewer cameras you are probably better off from a cost perspective using a DVR but if you anticipate your system expanding then cost alone is not your only criteria for comparison. But if you have a two DVR system--up to 32 cameras--then you will probably find that a server based system has the cost advantage if not initially then at least over the life of the system. And if you have three DVRs--up to 48 cameras--then you are definitely better off both initially and over time by buying the Acuity-vct server based system.

Even with a single DVR system, if you use a high end DVR and not some cheap import, over time the server probably has the edge.

Cost alone should not be your criteria for purchasing a specific type of system. With DVRs you are married to the manufacturer of that system. And four years from now when the model you have purchased is no longer on the market and one of your units breaks down, you will have no choice but to pay top dollar for service or buy a replacement model. But will the replacement model integrate with your existing DVRs? Many customers have reported that they had to replace all of their DVR instead of just the one that failed.

With a server-based system you can find service from any computer service provider. And if your server ever does need to be replaced you are replacing one appliance and not several. You can buy a replacement from nearly any computer product line.

Because a DVR is little more than a box to hold the hard drive, when a drive fails you are facing a costly repair. Most likely you will need to remove the DVR from the rack and disconnect all of its inputs and outputs. You’ll have to give your DVR to the repair tech or take it out for repair. Since the network is likely to be daisy chained from DVR to DVR, you’ll need to restore the network. Days later you will have to reinstall it in the rack and reconnect everything. The sixteen cameras connected to it will not be recorded or visible on a monitor while the DVR is out for service.

With a server-based system when a drive fails you can order a replacement via the internet and the next day it will arrive by Fed Ex. Simply pull out the bad drive cartridge and pop in the replacement and you will be up and running. While the drive was inoperable, images continue to be stored on other drives in the array.

The advantages of a server system over a DVR system are:

1. Cost

2. Power

3. Ease of Service

4. Reliability

5. Advanced Features

6. Efficiency of Design

7. More service options

In addition to the above advantages the Acuity-vct has advanced features not even found in the most powerful and expensive server based systems let alone on a DVR.


Want more?

Read how you use the Acuity-vct to protect a period room or historic house.

Read about the Library and Archive Reading Room Surveillance System.

Pros and cons of Digital Video Recorders vs. Server Based Systems

Read how the Acuity-vct system can be a back up to your alarm system.

Beware of Hidden Fees Charged by Many Manufacturers