Network-based: Network-based storage directly connects storage devices to the network without a fully- fledged server to run the video management system and other applications. Currently there are two kinds of network-based storage: Network Attached Storage (NAS), acting as a file server on the network, and the iSCSI (Small Computer Systems Interface), which acts as a hard drive on the network - enabling a server to write data to the iSCSI device as if was a local drive. Since today's network cameras essentially operate as servers, they can store video directly to the NAS or iSCSI storage device. This gives you the option of controlling the storage via the camera or a server.
Camera-based: Camera-based storage locates storage within the camera itself. Until recently, this was fairly uncommon. But with H.264 compression drastically reducing the size of video files, along with rapid increase of SD card memory capacity, camera-based storage is now a viable option. In-camera storage is mainly used at remote sites that only record limited amounts of video, or as fail-safe back up in case the network connection goes down. Camera-based storage also allows sites to buffer the video inside of the camera during the day when network bandwidth is limited and transmit it during off-hours to a central location for archiving.
Options for Building Redundant Storage
Today's IT systems are the backbone of many organizations. Think of an airport where air traffic control and passenger check-in operate 24/7 or a bank where transactions need to be managed across global time zones within seconds. Such applications put high demands on IT systems, requiring exceptional resilience and redundant availability. There are many ways to accomplish that failover profile, depending on the level of availability required and the budget available for the project.
RAID: In their simplest form, Redundant Array of Independent Disks (RAID) mirror each other. In a RAID 1 configuration, two disks store the same information so that if one fails, the other disk still maintains the identical information. In more advanced RAID 5 schemes, multiple disks share one common redundant disk, which is a more cost-effective use of storage resources.
Hot standby server: In a hot standby server configuration, you basically have two servers storing the same data and applications. If one server goes down, the other is immediately ready to take over because it houses an exact duplicate of the primary server's information and programs.
Advances in Storage Technology
Until recently, storage was a bottleneck for video surveillance and represented a very large part of the cost - not to mention a point of contention between physical security managers and their IT counterparts. Exponential advancements in storage media and architecture, however, are rapidly changing that.
More efficient H.264 compression, along with capacity doubling on a yearly basis, and more reliable solid-state storage media are giving users more flexible, redundant and cost-effective options than ever before. We have come so far with storage technology already that it makes the days of changing video tapes every eight hours seem like ancient history. In another 15 years, today's solutions and recording times will probably seem like ancient history, too.
Fredrik Nilsson is General Manager of the Americas for Axis Communications and author of the book Intelligent Network Video. He is a frequent contributor to STE, and his exclusive "Eye on Video" series is available at SecurityInfoWatch.com.