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Digital surveillance - the smart solution for security and monitoring

Video surveillance has grown to a booming marketplace, estimated to reach $46 billion by 2013, due in large to the migration of analogue to digital systems. A key differentiator of digital systems is the technology's ability to drive the costs usually associated with specialised surveillance systems.

Indeed, the ability to create a wide range of affordable digital video surveillance solutions using familiar storage controllers and disk drives will undoubtedly provide storage solutions providers with a legitimate claim on a share of the market. However, in order to substantiate digital storage's role in the surveillance industry, it is important that we take the first step in asking who is the typical customer and what do they need?

For one, a typical video surveillance customer might be a retail store that only has video surveillance because it is required for insurance and minimal security purposes. This company uses a single camera that records low-quality video to disk on the capture server, and every 24 hours begins overwriting yesterday's data with today's data.

The issue here is that for this typical customer and many other businesses, surveillance is a cost that can never be turned into a profit, the goal is therefore to minimise the solution cost. In contrast, a casino complex will run multiple cameras and save high-quality data for as long as 14 days before archiving it. For these usages, large storage capacity is required and reliability is tantamount.

At the highest end of the market are applications just coming into use by cities and airports that need to capture video and then process it with sophisticated image analysis that can detect objects or faces. The most advanced of these systems can identify objects or people in scenes and track them from frame to frame and camera to camera - this type of solution requires powerful processing.

At the heart of all the varied applications is the ability to maximise the investment and this is where storage advances come into play, as well as the ability of a solution provider to understand the varied video surveillance requirements.

Key differences of standard storage and video surveillance solutions

Today, a typical storage solution will have variable read and write patterns; in surveillance solutions writing is the primary concern. In instances where data is required to solve a crime or when a disk drive fails, the digital video surveillance solution must be able to accommodate reads and rebuilds without affecting the performance of the write operations that continue to record surveillance data to disk.

In the case of video surveillance, performance is an even bigger consideration. For example, with a single camera, the write speed of the camera determines the maximum performance of the solution. However, when another camera is added the performance dynamic is affected. Here, the storage controllers need to provide the throughput that will allow two camera streams to be transferred simultaneously to a single storage server. As cameras are added to the solution, this throughput requirement increases.

The most cost-effective way to accommodate multiple cameras is with a single controller that provides ample throughput to transfer all these streams to a single system of storage disks. Therefore, for those customers who may be starting with a single camera but anticipate the possibility of adding cameras, a controller that exceeds the maximum camera transfer speed is a prudent choice.

The other time when strictly matching controller performance to maximum camera speed may be a serious limitation is when there is the need to retrieve data, such as when a robbery or another crime has occurred. The ability to review previously collected data without affecting the current data recording is then a major consideration and this requires ample bandwidth to retrieve video if and when a disaster does strike. Naturally, for intensive applications such as tracking people and objects, maximum performance and processing power is required.

Reliability is another critical feature. And one way to ensure this is through the use of RAID. For customers whose primary concern is performance, RAID 1 makes the least impact on performance by simply mirroring data to a second set of disks. However, it incurs the cost of a second full set of disks. From an economical standpoint RAID 5 makes the most sense, since it removes only one disk per RAID set from active storage and stripes parity data across all disks for fault tolerance. With RAID 5, the video solution can survive the loss of a disk without losing data. However, having to calculate parity slows the write operation.

RAID 6 is similar to RAID 5, except that it requires two disks from each RAID set and provides the capability to survive two drive failures before data is lost. This can be critical if a second disk fails while a previously failed disk is being rebuilt. Importantly, controllers that rely on software RAID generally offer the lowest price point. However, software RAID places an overhead on system operations, requiring the CPU and operating system to carry some of the RAID load.

Depending on customer needs and RAID requirements, capacity can be another critical issue in creating a surveillance solution. Capacity starts at the disk level, where hard drives are being introduced that have been optimised for surveillance applications with capacities ranging from 250 GB to 1 TB. For customers with one camera who write over their low-quality data every day, a single capture server with a couple of disks and no other storage system might be enough. However, for those users who need to retain and archive data from multiple cameras, storage scalability is crucial.

While the most cost-effective high-capacity drives are SATA, a SATA-only controller forces a one drive to one port limitation on the solution. So, a 4-port SATA controller would connect to a maximum of four drives. On the other hand, a Unified Serial SATA/SAS controller incorporates a SAS interface that supports SATA disks and provides access to maximum scalability through the use of SAS expanders.

The simplest way to meet such a variety of customer needs is with a single family of controllers that offers models that provide the level of support that each customer requires, from the single camera store to the multicamera high-performance environment. As it is a single family, there is no need for additional testing, qualification, or training before you build new solutions.

In a nutshell, for vendors who are already providing storage solutions, the digital video surveillance market offers a natural opportunity for business expansion. The key would be to understand the marketplace's specific needs and deliver the features and solutions that meet it.

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