Barry Keepence, IndigoVision CTO, discusses the impact that a new breed of ‘green’ Network Video Recorders (NVRs) is having in reducing the hidden costs of storage for IP-CCTV systems.
Most financial models used for calculating storage costs in an IPCCTV system are based on the number of cameras, video resolution, frame rate, compressed video bitrate and archive period. The hidden costs of IP Video storage are largely ignored. Now, with the launch of new standalone ‘green’ NVRs, these hidden costs can be significantly reduced, changing both the financial model and the way system designers implement storage.
What are the Hidden Costs for IP Video Storage?
With the ever increasing need to record high-quality video at full-framerate, in some cases for 90-plus days and with the advent of High-Definition (HD) video being used in mainstream surveillance applications, it is not surprising that the storage element of a large IP-CCTV solution can dominate the overall cost of the system. When considering the cost of storage for a large IP Video system, several additional factors, affecting both capital and running costs, need to be considered, including:
Capital cost of power supply infrastructure, air conditioning infrastructure and rack space
Running costs for powering the recorders and powering the air conditioning system
Support and maintenance
Overall equipment footprint.
With a typical centralised NVR storage solution consisting of rack-mounted PC servers with attached storage, these hidden costs can be significant. In many organisations, energy costs have become the fastest growing operating cost, resulting in higher Total Cost of Ownership (TCO). Power consumption of CCTV equipment is not typically considered when designing a system nor is the operating cost of energy well managed, often with the organisation’s electricity bill not linked to the security operation – further hiding the costs of the surveillance solution.
Compared to a traditional server recording solution with attached disk-arrays, these units are very efficient, because they have been designed for a single dedicated task – continuous video recording and playback. Their small size and low heat output means they can be stacked vertically on top of each other in a 19-inch rack, requiring much less space. The low power consumption, equates to less heat, which means less air conditioning is required, further reducing running costs. With less air conditioning and less rack space, the overall equipment footprint is smaller. The video recording system can therefore be installed in smaller, lower specification rooms. IP video systems deploying centralised PC server storage systems will usually be sourcing the PCs and attached storage from different vendors. In the event of a problem or failure, the systems integrator will have to deal with not only the IP video system supplier, but also the storage vendors. This multi-vendor approach can lead to support and maintenance overheads, as there is no single point of contact. Using a NVR storage solution where all of the equipment is supplied by a single-vendor is therefore, clearly a benefit
Comparing costs
In a RAID 5 system, typical power consumption for a video storage server and attached RAID disk unit would be 900W, whereas the latest ‘green’ standalone NVR units typically consume around 50W. By expressing this in Watts per Terabyte, the system designer can better understand the differences:
Typical storage server solution: 40 W/TB
Standalone ‘green’ NVR: 9 W/TB.
This represents 78 per cent saving in power consumption, in addition to the lower air-conditioning equipment and energy costs. The storage requirements for a 500-camera system archiving continuous video at 4SIF 25/30fps for 30 days would typically be 300TB. With energy costs at US$0.10 KW/hr, this relates to an annual running cost of:
Typical storage server solution: US$10,512
Standalone ‘green’ NVR: US$2,365.
And this doesn’t take into account the extra power consumption of the air-conditioning!
Video compression
When choosing an IP video system, it is clear that the cost and performance of the storage solution is very important. By deploying ‘green’ standalone NVRs, many of these costs and performance issues can be addressed. However, still the most significant factor affecting the difference in cost between different vendors’ IP Video surveillance solutions is the quality of the video compression – and this often is down to how well the MPEG-4 or H.264 compression standards are implemented. This issue becomes even more important when considering megapixel HD video. The data rates from different manufacturers’ cameras can vary significantly, even when comparing cameras implementing H.264.
Architecture
The distributed nature of IP video systems allows NVRs to be at any point on the network. Not only does this provide for a more fault-tolerant configuration, i.e. removing the potential single-point of failure of centralised storage, but it can also reduce costs by removing the need for a costly air-conditioned equipment room. Single, standalone NVRs can simply be installed locally or mounted on a desk, in a normal ambient environment. Locating the storage at the network edge also reduces the bandwidth demands on the network, further reducing costs.
Analytics – reducing amount of video
There is no point in recording video from a camera at full frame rate if there is nothing in the scene to record. By using applications such as IndigoVision’s unique Activity Controlled Framerate (ACF), the amount of video and storage can be significantly reduced. When a scene is inactive the video can be streamed at a much lower frame rate. As soon as the motion analysis software detects movement the video is streamed at full frame rate. Similarly analytics such as virtual tripwire can detect an object crossing a line and raise an alarm. This alarm can start a recording, possibly selecting a higher frame rate stream from that particular camera.
Data security
Another hidden cost is associated with data security, and the cost of losing video. With so much valuable data being recorded it’s important to consider NVR security and reliability. Most NVR storage solutions will deploy RAID disk arrays. A Redundant Array of Independent Drives (RAID) is an umbrella term for computer data storage schemes that divide and/or replicate data among multiple hard drives. There are different RAID levels, giving different levels of protection. In a RAID 5 configuration of four disks for example, the data is striped across three disks and the fourth disk stores recovery data (parity). If any one disk fails no data is lost and the recording system can continue without interruption.
Dedicated NVRs take security a level further. These robust hardware units have redundant power supplies and network connections, RAID configurations and hot-swappable drives. An NVR backup strategy can also be configured to add redundancy to the system. For example, if an NVR failure is detected by the system software, recordings can automatically be switched to a backup NVR or distributed amongst other NVRs in the system. Like disks within a RAID array, entire NVRs can be mirrored, with the same video being recorded on two NVRs simultaneously, providing the highest level of security.
Summary
Many organisations have very focussed environmental policies and are keen to deploy energy efficient solutions wherever possible. The standalone ‘green’ NVR storage solution satisfies this environmental requirement, as well as reducing running costs. This coupled with the other advantages of fault-tolerant dedicated NVRs means a shift from large centralised PC-based server racks for video recording is inevitable.
About the author
Before joining Edinburgh-based IndigoVision as Chief Technical Officer (CTO) in 1999, Barry Keepence worked for over 10 years in the Space industry and at 3Com as a System Architect.
