From The Edge To The Cloud

Storage is an important consideration for any video system

• By Robert Kramer
• Jul 01, 2012

System designers must ensure that sufficient storage is available to archive video for the required length of time and at the required frame rate and resolution. Changing technologies in today’s market are altering storage needs, making it essential for designers and integrators to maintain their expertise so that they can best advise their customers on the right storage solution to meet their needs.

Traditional storage options include DVRs, a standard piece of an analog system and NVRs, typical for IP systems. Both DVRs and NVRs have internal harddisk drives (HDDs) that provide storage, and expansion devices can be used if more storage is needed. Today, storage solutions are migrating rapidly to incorporate cloud-based solutions, as well.

Enhancing Access to Stored Video

Today’s more intelligent solutions enable recorders to provide additional value with greater functionality related to retrieving video. User interfaces have evolved and now offer capabilities such as intuitive search features to review video based on a calendar and timeline and flexible playback controls that allow users to jump to a specific time/date or to a variable number of seconds before the end of a recording. Filtered searches can target time and date, event type and camera number.

Some new NVRs feature even more advanced capabilities, including embedded face-matching technology that compares face images obtained from a connected network video camera (equipped with face-detection capability) with faces previously identified and stored in the video recorder. When a match is found, an alarm notification can be sent by email, system alarm, terminal output, buzzer or indicator. This capability, designed as a security solution for small retail and other specific environments, demonstrates an added-value approach to using stored video. Additional software capabilities also can be used to count visitors, track visit times and even estimate the age and gender of people captured on video. This new functionality could help a retailer track customer patterns, and it can provide useful demographic information.

How Much Storage is Enough?

Advanced functionality is dependent on a recorder’s ability to store video. But how much storage is enough? Too little storage undermines system performance, and too much storage can be a waste of resources and increase system costs. Determining the required storage involves a simple calculation based on the number of cameras, the data requirements of their image size and frame rate, the effectiveness of compression and the number of days of recordings to be saved to meet the application needs.

Real-time video at 30 fps, especially from a megapixel camera, for example, requires a lot of storage to retain evidence for 30 days, which is a standard in many applications. Less storage is needed if a slower frame rate is acceptable, if a lowerresolution image is sufficient—especially in off-hours—or if retaining video for a day or two is sufficient. Careful analysis by the integrator, combined with discussions with end users about how they will use the system, is the best approach to evaluating storage needs.

When additional storage is needed, the most basic option is to use directly attached storage (DAS). This often takes the form of expansion storage provided by the DVR/NVR supplier. Each DVR/NVR uses its own DAS to archive video from its connected cameras. Additional storage can be added to an NVR by installing additional HDDs and using expansion units.

It is interesting to note that server and storage solutions have made great strides in energy efficiency over the last five years. At one time, HDDs were among the largest energy-usage components in a large server or storage solution. Today, HDDs’ power usage has dropped by half compared to five years ago with the adoption of more efficient motors and better circuit-board technology. A host of software technologies now monitor HDD efficiency, adjust settings and use smart control so that HDDs spin up to full speed only when needed while other drives remain idle or spin at a slower speed. As solid-state HDD capacity increases, it can eventually replace the higher-power requirements of spinning motors used in current HDD technology.

Network Storage Options

Today’s IP-networked video systems provide other options when it comes to storage, including network-attached storage (NAS) and a storage area network (SAN). A networked device that contains one or more HDDs, often arranged into a redundant array of independent disks (RAID), NAS is a single storage appliance that supports multiple servers in a network. The NAS devices maintain their own IP addresses and can be set up to share files among various users on the network.

Another storage choice is SAN, which is suitable for large networks that require a lot of centralized file storage or very high-speed file transfer operations. Rather than using multiple NAS devices on a network to meet storage needs, a system administrator may choose to use a single SAN with a highperformance disk array to provide the needed scalability and performance.

Storage in the Cloud and at the Edge

An emerging option for IP network storage that has intriguing possibilities for video applications is off-site storage, also known as SaaS or cloud storage. Video storage is provided as a service over the Internet by companies using massive data centers around the world that provide unlimited capacity and 24/7 access. This approach is an emerging trend in the video surveillance arena because of lower costs and multiple advantages.

Cloud-based video storage is priced at a fraction of what network storage devices cost when measured per gigabyte. The cost-savings alone suggest a growing role in the future for this type of storage. The security of video images stored off site is a top priority for cloudbased system suppliers, offering another potential advantage of this solution.

Access to cloud-based storage across the network may be similar to how an NVR accesses on-site network storage. Another scenario involves accessing off-site storage using a cloudbased software application that takes the place of an NVR. Off-site cloudbased storage can be useful as a backup in case local systems go down.

Storage also is available inside the camera itself. Many cameras provide SD/SDHC memory card slots that enable use of computer chips to provide manual recording, alarm recording or backup JPEG recording if the network fails. This capability at the edge of the network provides backup recording in case a system goes down, and it can be a localized complement to cloud-based storage. Edge-based storage can also mitigate the bandwidth requirements of a system.

Ensuring Seamless Operation

Market developments such as megapixel cameras and new video compression standards continue to impact the storage needs of current and future video surveillance systems. Understanding the technologies and the needs of each application directs the selection of storage options. Integrators and end users can continue to look to manufacturers to be at the forefront, ensuring that technologies work seamlessly with all the various system components, including storage.

This article originally appeared in the Security Products Magazine - July 2012 issue of Security Today.