The state of storage

The analog-to-digital surveillance system evolution is being driven by technology innovations and the promise of significant market growth and the higher revenues that accompany it. Today's H.264 video compression capabilities, fast networking connectivity and megapixel cameras provide a strong basis for transition to digital-based systems. As these innovations are advancing surveillance capabilities, they are also creating the need for more capacious storage. An eight megapixel camera can produce one terabyte of data in just three days. Even with strides in video compression, the surveillance community is constantly looking at how to cost-effectively integrate these increasingly data-intensive cameras with standalone video recorders. High capacity AV-class hard drive storage has quickly become an industry-enabling design element necessary to sustain a workable digital solution.
Industry analysts have predicted that transitioning security surveillance systems to digital from analog is the most important challenge facing the security video market. The digital video revolution has opened the door for camera resolutions to increase at an even faster pace. This is why it is essential that security system integrators have a clear understanding of the optimal storage capacity and possible system compatibility issues for a given video surveillance application. Integrators need a method for calculating storage needs based on video resolution and standards, recording hour requirements and the number of cameras used in the system.

Hard drive innovation

Hard drive storage is the platform that facilitates the move from outdated and cumbersome tape-based systems to digital systems. Due to constant innovation, hard drive manufacturers have consistently delivered increased storage capacity while keeping prices affordable. Audio/video (AV) surveillance and security applications can take advantage of these huge technology achievements that have made hundreds of terabytes or even petabytes of storage available. AV-Class hard drives have been engineered to not only provide the performance necessary to access and retrieve stored video quickly, they can also deliver the high capacity points that enable higher resolution video streams to be stored more efficiently and cost-effectively. Western Digital is committed to serving the security market and was the first to introduce a two-terabyte drive designed for surveillance. This landmark capacity point enables surveillance systems with two or more cameras to record high levels of clarity (30 frames per second) at a broad range of resolution settings and still store 30 days or more of video footage.

Using high-capacity surveillance drives will become even more important as high definition (HD) becomes increasingly pervasive. Capacity is by no means the only enabling hard drive innovation for the surveillance market. Other elements include lower thermals (and therefore higher reliability and longer product life), low power consumption, inaudible 24x7 operation, universal system compatibility and the ability to simultaneously record multiple audio and/or high-definition video streams.

High reliability and product longevity

Storage reliability is paramount to maintaining long product life of surveillance systems. Today's hard drives for surveillance systems have been specifically designed and tested for long product deployments in always-on streaming digital audio/video environments. Drives that have been specifically designed for these intensive applications typically feature a high Mean Time Before Failure (MTBF) of 1 million hours, which is higher than desktop or notebook PC hard drives. Advanced hard drive technologies that help ensure system longevity and endurance are also available such as Preemptive Wear Leveling (PWL), which has been integrated into several hard drives from Western Digital.

It is important that any storage solution be tested to ensure universal system compatibility with a broad range of AV/surveillance and security products including set top boxes, DVR recorders and other mainstream surveillance systems. It is crucial that the AV-class hard drive not only be universally interoperable, but also optimized for smooth, continuous digital video playback.

Hard drives specifically designed for these applications can now handle as many as 12 simultaneous high-definition streams and are based on the industry-standard ATA specification for universal compatibility. Mainstream surveillance video recorders save images at a slower pace than high-definition video and in that application hard drives can record up to 16 standard-definition streams.

Calculating storage needs

The type of video transmission technology used is one of the main factors affecting storage capacity requirements. Transmission technologies range from being non-compressed and very data-intensive to highly-compressed and moderately data-intensive. The H.264 compression format established itself as a mainstream video compression format that can significantly reduce the size of a digital video file as compared to other compression algorithms. As H.264 becomes more prevalent, it enables higher resolution to be affordably stored on similar capacity drives. According to IMS Research, if all the tools are implemented that the H.264 compression standard supports, it can save up to 30 to 50 percent of the network bandwidth and storage needed when compared with using MPEG-4 video compression. For those companies that choose to stay with non- or less-compressed video formats, demand for high capacity storage will be even stronger.

In addition to video compression, storage capacity is also affected by video stream resolution, frames per second or the image quality along with the length or quantity of streams and how long they will be needed to be available or archived. It is important to note that not all businesses require a high resolution video surveillance system. The ability to use fewer cameras at a lower resolution in many environments decreases the amount of capacity needed to store the video images. Using less storage capacity enables businesses that do not need high resolution in an "always on" operating situation to substantially increase the archival life of the video stream, enabling a reduced total cost of ownership of their overall surveillance system.

Digital-based AV/surveillance and security applications are expected to grow at a healthy pace, and the good news is that system integrators can grow along with this expanding market. High capacity AV-class hard drives have evolved as one of the significant technology enablers for the surveillance industry. The broad base of industries that see video surveillance as an essential part of their business is quickly realizing the benefits of transitioning from analog tape to digital-based systems. Important benefits for system integration include the ability to access and archive content faster, ease of content management, improved overall image quality and lengthening the time and amount of data that can be recorded. With continued technology advancements, AV-class hard drives optimized for the surveillance market will help surveillance OEMs and integrators better manage their product offerings. These storage innovations provide integrators with the foundation to build optimized, cost-effective and long-life solutions for their growing list of video surveillance system customers.


To properly calculate storage needs, the following considerations need to be addressed:

- Video compression used on the camera stream
- Camera resolution
- Number of cameras deployed
- Video quality desired
- The frames per second rate of each camera
- Number of hours each camera will record per day
- Required days/hours of archived storage
- Total network bandwidth required

Ed Strong is the marketing director of AV Storage for Western Digital, Lake Forest, Calif.