Remember the days when your surveillance system was a handful of analog cameras and a clunky VCR?
Those times were simpler, but video cassettes have gone the way of 8-track tapes and floppy disks.
Today’s security systems have the same sophistication as your building automation system.
While security may seem on the margins of your FM duties, surveillance cameras and recording devices are nonetheless physical assets that are connected to your building’s infrastructure. Make sure you have a firm handle on this technology.
Rich Cecchini, a storage expert with Seneca, a systems manufacturer, and Jonathan Lewit, senior product manager with Pelco by Schneider Electric, a surveillance solution provider, share their insights on video storage options.
How has video storage for surveillance cameras changed over the last decade?
Cecchini: Video storage started as cassettes with tape selection and long waits to view video sequences. Then we moved to piles of DVDs, which still had similar playback problems. Now we use disk arrays that can hold 1,000 times the capacity of the old options and have instant access to recorded video. Advancements in video storage have also created changes in security video management software. These tools allow network-connected digital cameras to use traditional network infrastructure, which greatly reduces capital and operating expenditures for surveillance.
Lewit: The size of a single hard disk drive (HDD) has increased dramatically, making 4-, 5- and even 6-terabyte drives fairly common these days. A decade ago, an entire digital video recorder (DVR) might approach that kind of data with multiple disks. Now we have the ability to store higher resolution videos at closer to real-time frame rates.
Do storage options differ between camera models, such as analog, PoE, IP, and wireless?
Lewit: From a video management system standpoint, each of these cameras still generates a video signal that can be represented as bits and stored on an HDD. Analog cameras need to be run through an encoder device to translate the continuous waveform into its digital representation. On the wireless side, you may have to take into consideration the bandwidth available for streaming, but once that stream is on the network, it can easily be routed to disks managed by the appropriate network video recorder.
Cecchini: Keep in mind that storing video is completely different than connecting cameras. However, analog cameras generally have lower resolutions and therefore consume less storage space than more modern higher resolution cameras. IP cameras are typically connected via Power over Ethernet or wireless Ethernet, which minimizes the infrastructure needed for a successful deployment.
What kind of storage is available?
Lewit: There are a variety of internal and embedded storage options. Increasingly we are seeing the presence of storage local to the camera, typically in the form of a secure digital (SD) card, although some cameras support connecting to an HDD or solid state drive (SSD).
This enables interesting deployment opportunities where cameras can essentially buffer information at the edge and only transmit high capacity data when requested by the system or client. Alternatively, the onboard storage can also be used as a redundant storage location for data in the event of network or other system storage failure.
Cecchini: Direct attached storage, or DAS, is ideal for inexpensive use of today’s largest disks. DAS drives and enclosures can enjoy the same RAID protection afforded by internal drives and centralized NAS or SAN appliances. DVR and NVR are merely the recorders that storage can be attached to. These can be embedded, internal, or external. NAS and SAN are network-connected storage devices that one or more recorders can use to save and retrieve video.
How does a building owner decide which storage option is the best fit?
Cecchini: There are a number of factors that can be combined for the right solution or become the system’s limitation if they aren’t properly accounted for.
Scalability is the ability to grow or increase capacity. Even the most economic storage solution, DAS, can scale to over 100 terabytes per recorder, but flexibility and sharing are limited when compared to a SAN/NAS centralized storage answer. You also want to increase size conveniently. In this case, it’s preferable to use advanced SAN/NAS storage appliances where space can be more easily increased and even transparently expanded to the recorders.
Storage periods or data retention length affect how much capacity is required. Longer storage periods equal higher video capacity demand. With a DAS solution, a capacity requirement either can or cannot be met. With a SAN/NAS solution, however, you have to look at capacity and scalability. While SAN/NAS capacity is generally much greater than DAS, the appliance must also be able to grow to meet the future size requirements as other recorders are added to the network.
Bandwidth is another consideration. Generally speaking, higher total camera bandwidth generates higher storage requirements. While capacity, storage periods, and scalability are part of the equation, performance has to be considered as well. Bandwidth on the camera side also impacts the server and storage performance requirements. If the storage subsystem is too slow, video frame loss will happen. Even worse, huge chunks of video can be lost and system crashing can occur if the problem is acute.