Application characteristics of storage equipment of security video surveillance system

The video monitoring system generally has many monitoring points, a large number of cameras, and a long monitoring time, and the time for collecting data is often as long as several days or tens of days. The storage devices used in video surveillance systems have different characteristics from other types of systems in terms of data read and write methods.

Features:

1) The digital video encoder or video server writes the data to the storage device in streaming mode, the images and pictures returned by the real-time monitoring point are stored in storage in streaming mode, and the playback workstation reads the stored data in streaming mode Video files. This reading and writing method is completely different from the small data block or file-level reading and writing method used in ordinary database systems or file server systems. Therefore, the video monitoring system storage differs greatly from other application systems in terms of technical parameters.

2) There are often 2000-3000 or even more surveillance cameras in large-scale video surveillance systems, and each camera generally uses the D1 format to return images. The code rate of each D1 image is 2Mb / s, and all cameras need to add up to a total bandwidth of 500-750MB / S.

During the video capture process, the video file format generally does not change, and the bit rate remains constant. The frame rate of the video image is generally between 15-25 frames / S, which means that in the storage read and write operations, it must be It is guaranteed that the bandwidth of 500-750MB / S can be reached every 1/25 second, otherwise frame loss will occur in image acquisition or playback, unless the storage device itself is configured with a large-capacity cache. Therefore, video surveillance system storage requires not only large bandwidth, but also constant bandwidth.

3) The duration of data read and write operations is long. Since the camera generally works 7 * 24 hours, even if the streaming media file is saved in segments, the duration of the write operation may be as long as 2-6 hours, and the same time is required for later playback. Therefore, storage is required to have super long-term work ability and maintain long-term stability.

4) Video surveillance systems generally have a large number of cameras and long storage time of video images, so the storage capacity requirements are huge, and as the image storage time increases, the storage capacity requirements increase linearly and explosively. Therefore, the storage of the video surveillance system must support large capacity, and the capacity has high scalability to meet the needs of long-term large-capacity video image storage.

5) The digital video encoder generally provides a standard IP interface or iSCSI interface to the outside, and transmits data to the rear monitoring center by transmitting TCP / IP protocol packets or iSCSI protocol packets on the ADSL, metropolitan area network, or private network. If the storage device has the same interface as the digital video encoder, the encoder may directly write and store the data, which will greatly reduce the data transmission link of the monitoring system and provide the efficiency of data storage.