Choosing video storage systems
Choosing a video recording technology for customers is not the relatively simple decision it once was when VCRs were the only option. Today, the technologies available include embedded DVRs, PC-based DVR, Hybrid DVR/network video recorders (NVR), embedded NVR and NVR with network-based storage.
August 4, 2009 By Kathleen Sibley
DVRs use proprietary technology, can’t be easily upgraded or serviced
and typically record analogue video signals. They store video directly
on their hard drive, so storage is limited. But they’re easy to install
and use, and for many customers, they are a perfectly adequate solution.
NVRs digitize video content and send it in Internet Protocol (IP)
packets over the Internet. They can be used with multiple IP cameras as
well as with most analogue and PTZ devices at the same time, and can be
located anywhere on a network. NVRs enable a wide range of centralized
and distributed storage options that can be expanded as required.
Until now, a standard rule of thumb for deciding which video recording
technology to choose has applied, say experts: if it’s a fairly small
installation that is unlikely to require additional storage in the
future, either for higher-quality video playback or longer-term
retention, the digital video recorder (DVR) remains the most popular
According to MultiMedia Intelligence, a Scottsdale, Ariz.-based
research firm, traditional embedded DVRs still dominate the overall
video surveillance storage market, comprising 62 per cent of the
approximately US$2 billion market in 2007.
And while IP-based security products are revolutionizing the security
market, physical security professionals are not typically
revolutionaries, the report says. Nor are they experts in networking
and IP technology. That means adoption of NVR technology has been slow.
“All the buzz is about IP, but 90 per cent of the business done daily
is still analogue,” says Dave Smith, senior vice-president at Samsung
According to Smith, IP is now used in situations where analogue is not an option due to geographical factors.
“I think the majority of IP-based applications should be looked at as
new business for the industry,” he says. “Most of the business in the
last five years has been business that wouldn’t have had a CCTV system,
because it couldn’t have been done by analogue.”
There are other reasons, however, for the continued popularity of
analogue DVRs, and it’s not just that the security industry has been
slow to shift to the networked world.
Vendors such as Genetec, a pioneer in NVR technology, recognize that
many customers are not ready to just discard the investments they’ve
made in DVR technology, especially in today’s economic environment.
“When we first decided to build an IP solution at Genetec more than 10
years ago, analogue systems were still very present, so we had to
design a system that could not only start moving the market towards IP
technology, but also make sure the investments customers had made could
still be used,” says Genetec product manager Francis LaChance.
To meet that requirement, Genetec, and others, began designing an offering that can
retrofit existing analogue cameras for an IP network by using video
encoders to convert analogue signals to MPEG4 digital signals.
“The NVR system will manage that as if it were IP,” he explains.
Although approximately 60 per cent of all new Genetec sales are of
IP-based video surveillance technology, says LaChance, “today, if you
take a snapshot, probably 35 per cent of the market is still analogue.
So it’s important to give customers the ability to use existing systems
with the option to start the migration slowly.”
ADT Advanced Integration/Intercon Security in Toronto is a case in point.
Terence Kilgore, manager, presales engineering, says while Intercon now uses mostly NVRs, it still uses DVRs as well.
DVRs are cheap and easy to implement, he says, but there’s a risk to
having everything — encoding, decoding, the image database and user
interface — in one basket. “If the DVR fails, you lose everything,” he
says. “Then there’s the fact that DVRs are not really expandable. If
you run out of storage, you’re going to overwrite video or you have to
go through the fuss of archiving it into long-term storage media.”
NVRs also make it easier to add additional devices such as cameras.
“With a DVR, if you get a 17th camera, you have to get another DVR.
With an NVR, if you get a 17th camera, you just add it on the network,”
Plus, you can use industry-standard storage with NVRs, he adds. “You’ve got all the variety that’s available to the IT world.”
You’ve also got all the complexity. Security professionals, therefore,
have to know a lot more about issues such as bandwidth throughput when
they use NVR technology.
“Your bar for delivery knowledge has to be so much higher,” Kilgore says.
To close that knowledge gap, Intercon hired an IT networking expert
several years ago and trained him on physical security. That was
easier, he said, than trying to teach a security expert everything he
or she would need to know about IT.
“If you’ve got someone who lives in the IT world, the learning curve is
nowhere as steep. The security guys have to wrap their head around a
whole lot more.”
Size of installation is one factor to consider in choosing recording
technologies. But storage, both size and architecture, is another.
To determine a client’s storage needs, explains Rob Simopoulos, partner
at Sonitrol Security Systems in Burlington, Ont., you have to take into
account the period the video must be stored and the quality of playback
Other factors include frame rate and the efficiency of the compression algorithm that will be used to encode the video.
Most Sonitrol clients need to store video for 30 to 60 days, although
the firm has had requests for systems that can store video for one to
two years, he says. “Typically we’re deploying 2 to 3 TB for a
relatively decent-sized system that does not need long-term storage,”
Video can be stored in a centralized architecture, meaning all storage
resources are combined into a central pool, either locally or at a
remote data centre, or in a distributed setup, in which storage is
directly attached to individual servers throughout the network.
The benefit to using distributed storage, says Simopoulos, is that it reduces the risk of video data loss.
In a centralized storage scenario, “If you’re trying to bring back 100
cameras on a humongous network and if one of the networking switches
goes down in that process, you can lose a huge group of cameras being
recorded,” he says. “By having the storage distributed in different
locations on the network, if one portion of the network goes down, you
won’t lose a huge batch of cameras. If it’s set up properly, you’ll
still be recording the majority of the cameras.”
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