Regardless of the architecture that is appropriate for each IP video deployment, a well-designed project will also feature contingency plans for potential system weaknesses. Distributed architecture systems overcome network down-time simply by its independence from the network for continuous recording. For an NVR-based system, technology exists that provides automatic and consistent replenishment of the network once a network failure has been restored, preventing momentary losses of video from exposure due to wireless transmission. Integrators should look for this technology in conjunction with the ability to record video locally using an internal hard drive or other media (such as a compact flash card) that can fill in the gaps when the encoder was unable to transmit video to the central NVR.
Already, security system manufacturers have begun to introduce video recording managers that distribute video across various iSCSI disk arrays on the network. If one disk array unit fails, the recording manager will simply redirect video data to a backup device. This approach to video management will result in better disk utilization, better load balancing and greater reliability. The throughput will also be greater because of the elimination of the NVR as part of the architecture.
For integrators, the benefits of using a video recording manager are a simpler architecture with fewer items that can fail and less hardware and software for IT personnel to manage. With this type of system, integrators can avoid using NVRs.
A well-designed IP video project will also take into account the combination of solutions in order for maximum flexibility and customization to the system owner's needs. For example, both architectures (centralized NVR and decentralized RAIDs) can be combined. Such a move might pair recording at the edge [such as at for some remote locations which are connected with a low-bandwidth WAN] with other locations that feed video centrally. While each topography has its advantages and drawbacks, today's growing array of solutions gives the integrator more options for system design and improved ability to meet their customers' diverse requirements.
About the author: Dr. Bob Banerjee is the product marketing manager for IP video products at Bosch Security Systems, Inc. He has extensive experience in advanced hybrid analog and digital CCTV solutions and has developed Bosch's IP Resource Center found at www.boschsecurity.us/ip. He can be reached at (717) 735-6637 or firstname.lastname@example.org.