Video and data are not created equal

A review of the reasoning behind an iSCSI recording implementation


"I cannot imagine any condition which would cause a ship to founder. I cannot conceive of any vital disaster happening to this vessel. Modern ship building has gone beyond that."
- Captain Smith, Commander of the Titanic

This quotation is a foreshadowing that not only applies to ships at sea, but also to networks of any size. The iceberg that may lurk in your future is CCTV video, if it is treated like regular data. Video is a unique creature with nuances of its own, and those can be very mercurial based on the implementation and specific deployment.

In the mid-1990s, the CCTV industry slowly started its digital convergence with the IT industry, and the merger has now reached staggering speed -- outpacing the knowledge base of most CCTV integrators, installers and contractors. Most integrators will not pay IT industry salaries to their field technicians, preventing qualified IT techs from entering the security industry. That, coupled with the fact that IT now has the biggest say about the products being deployed on their networks, results in more IT departments taking ownership of their CCTV security systems.

About a decade ago, when I found my way into the security industry, I was an anomaly -- the computer "geek" in the analog CCTV world. Moving from my role as a network administrator in the Marine Corps to a CCTV technical instructor was truly a culture shock. My previous world was about data flow (speed), data security, and long-term storage. The CCTV world is based on the same data principles, but the two types of data were and still are very different in terms of sheer size and volume.

Simple Math
The industry then, as well as some vendors' perspectives now, is to treat video data like any other type of data and store it in a centralized fashion. ("Captain Smith, I think we should turn SOUTH just a bit!")

In most of my seminars and presentations, I usually equate video and data to ice. Data is like a cup of ice cubes, while video on a large system is the iceberg that sank the Titanic. Let's do a simple comparison to show you what I mean.

For a point-of-sale transaction database with 100 million records, you would need roughly 80GB of space, depending on the vendor application and the type of database used. Since a transaction is a change to the database (add, change, delete), theoretically, we could run trillions of transactions against that same 80GB database. So, the first set of numbers for our comparison exercise is:
POS 80GB = 100 million records with 1 trillion transactions

For the second portion of our comparison, let's look at data that most of us are more familiar with. We have an Exchange Server with 2,000 users, and each user has a 150MB mailbox. That would give us roughly 292GB of needed storage. So, our next set of numbers is:
292GB Exchange Space = 2,000 users

To get the third number, we are going to look at only one IP camera. We will use some numbers from a very common specification for video: 30 FPS at 4CIF (H.264) with an average bit rate of 2,000kb/s with no quiet time. We want to record this camera and retain the video for 30 days. This number is:
679.8GB = 1 camera for 30 days

So, from a storage perspective, we have three very different numbers that help us see the basic difference between video and data -- 80GB, 292GB and 679GB.

Now, consider the numbers involved in a surveillance system at a medium-sized international airport that has been installed for a few years now. Here are the specifications:
300 cameras, 15 FPS @ 4CIF (H.263/MPEG4), max and target bit rates of 1500 kb/s and 1200 kb/s, with 30 days retention time

This installation requires:
135 TB + failover devices (20 TB in back up storage) for a total of 155 TB

So, just imagine the storage required for a truly large installation with more than 2,000 cameras and retention time close to one year!

This content continues onto the next page...