High-Volume Storage

The demands on video surveillance systems have grown dramatically in recent years. Improved video quality, higher frame rates and the need for longer retention periods for recorded video have led to a significant change in the storage that video...


By far, the biggest difference is in workload. IT systems are typically generalist solutions, designed to run a balance of read (from disk) and write (to disk) activities for applications such as databases, human resource management, sales, payroll, engineering, manufacturing, etc. They typically run in batch (all at once) or online transaction processing (such as database updates), and multiple applications typically run on the same computers and storage.

Video surveillance workloads differ greatly. They typically run a single application flat out, recording (writing to disk) 95-98 percent of their operational time. Only 2-5 percent of the time is spent on playback (reads from disk), and that typically is only when an incident occurs. To perform at their best, video retention systems need to be tuned for near-constant recording. Unfortunately, this unusual and demanding workload challenges IT storage simply due to design differences.

The solution is to select a storage product that delivers the power of shared IP storage from the IT world, but that delivers a design specifically for physical security as the primary application — not an add-on.

Security users often deploy commodity servers to host VMS systems and support direct attached storage. Unfortunately, doing so will usually require more hardware than opting for a shared, external IP storage solution.

Consider the example of a major municipal electrical utility in Texas. The requirement was to support three different brands of IP and megapixel cameras providing coverage across a large geographical area and multiple facilities. Starting with 90 cameras and expected to grow to 300, the utility selected one of the best known VMS vendors. Sizing the hardware, they found they required 18 commodity servers with a total of 128TB raw capacity. The cost was stunning, nearly a quarter of million dollars.

By opting to instead use shared IP storage, enormous savings were achieved. The number of servers shrank by nearly 90 percent — from 18 to just two (see figure 1, page 40). And that meant the storage could be reduced by nearly 80 percent, with just 30 TB required. Reliability was dramatically improved, with OEM-grade drives and components designed into the video-optimized solution, eliminating downtime and the risk of lost video. The total cost reduction of about 70 percent cut the price to just $70,000. The green benefits of reduced power consumption — less to heat and cool, and much less hardware to manage and maintain — added even further savings.

Outside of physical security, large storage requirements are nothing new. In IT, storage capacity has been growing for decades, with succeeding waves of technology to better address requirements. Like today’s DVRs, the first IT solutions used direct attached storage (DAS) captive to a particular application server. This was replaced by the idea of sharing storage to improve performance, benefit from quantity of scale and improve reliability. Network Attached Storage addresses this for IT workgroups and departments, although performance, capacity and administration can be challenging when users try to grow into larger deployments. Instead, Storage Area Networks are commonly used for higher-performing, large-scale needs.

Originally, fibre channel SAN was the only choice, which restricted use to large data centers. When less expensive but equally scalable and reliable IP SAN came along, it was possible for customers that previously could only afford to deploy DAS or NAS to benefit.

Emerging Choices

The example illustrates how using IP SAN benefits security users over DAS and commodity servers. Yet there is still another technology wave coming from IT that is making itself known in video surveillance — virtualization.

Virtualization is a simple concept. Instead of running two or more applications on separate hardware platforms, virtualization enables organizations to host the applications simultaneously on a single, larger server. It cuts costs, improves reliability, reduces maintenance and dramatically “greens” a system by reducing power consumption, heating, cooling and equipment needs.

Going back to the earlier example, 16 of 18 commodity servers were cut with cost savings approaching $200,000 for hardware alone. What would be the impact if we could cut out those two remaining devices?