Even in the era of VCRs, video storage was a challenge. In those days, storage sometimes consisted of rooms full of VHS tapes that were carefully organized and scrupulously rotated to keep video for a specified time period. Fast forward to today, in which multiple options for digital storage offer a vast improvement by providing greater resolution and instant access to video clips without time-consuming rewinding or fast-forwarding. For integrators, leveraging the maximum benefit of the newer technologies does require more education about what is available in the market, along with analysis of the application needs, to find the perfect storage solution.
DAS, NAS, SAN and more
It can be a delicate balancing act to ensure there is enough storage space for an application while avoiding the pitfalls of specifying too much, which can increase system costs unnecessarily. Determining the required storage really amounts to a math formula: the calculation is based on the number of cameras, data requirements of their image size (in KB) and frame rate (in frames per second or fps), the effectiveness of compression and the number of days of recordings which are required to be saved to meet the application specification.
The simplest type of storage is direct attached storage (DAS), which means the storage is connected as a hard disk drive (HDD) to a server or network video recorder (NVR). Each NVR uses its own DAS storage to archive video from its connected cameras. Additional storage can be added to an NVR by installing additional HDDs and using expansion units.
Today's networked video systems also provide other options when it comes to storage, including network attached storage (NAS) and a storage area network (SAN). NAS is a single storage device that serves multiple servers or NVRs in a network. The NAS maintains its own IP address and can be set up to share files among various users on the network. This networked appliance contains one or more HDDs, often arranged into a Redundant Array of Independent Disks (RAID).
SAN is another storage choice 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 high-performance disk array to provide the necessary scalability and performance.
An emerging option for network storage that holds possibilities for video applications is off-site storage, i.e., Storage as a Service or "cloud" storage. In this case, storage is provided as a service over the Internet using massive data centers around the world that provide the necessary capacity and 24/7 access. This approach isn't currently common in the video surveillance arena but the low cost-a fraction of what network devices cost when measured per gigabyte-suggests there may be a role in the future for this type of storage.
In the future, the storage needs of systems are likely to continue to progress in lock-step with technology changes in the industry. Integrators and end-users will also continue to depend on manufacturers to ensure that their technologies work seamlessly with storage and all the various system components.
