"Veracity's patented LAID (Linear Array of Idle Disks) form part of a storage system technology using standard hard disks and was designed specifically for video surveillance recording applications. The basic principle exploits the real-time nature of the application - that video is generated sequentially, even though many channels of video can be generated simultaneously. Video is recorded to a mirrored pair of disks, overlapping sequentially across the array. This allows all other drives in the array to be switched off, saving power, wear and lowering temperature and vibrations. Writing starts off with disk 1 and 2 as the mirrored pair, giving full writing redundancy. When they are filled with data, the writing switches to disks 2 and 3, commencing overwriting data on disk 2 and preserving the data on disk 1. As the disks are filled, the writing pattern moves across the array, to 3 & 4, 4 & 5, 5 & 6 and so on until the end of the array is reached (say disks 15 & 16). At this point the writing wraps around to use disks 16 & 1 as the mirrored pair, and the sequential writing process across the array repeats ad infinitum. Obviously, as with any disk array used for surveillance recording, the total disk capacity in the array must be sufficient to meet or exceed the desired retention period of 30, 60 or 90 days for example. This LAID concept is implemented in Veracity's COLDSTORE range of storage products, and has many compelling advantages over convential RAID systems. These include dramatically increased disk lifetimes, 5 to 10 times lower power consumption, no disk rebuilds, suited to the maximum capacity drives available, plus removable disks which preserve the recorded data, for evidential and archive pruposes. "