Video surveillance covers a wide range of areas including finance, military, government, customs, transportation, community, office buildings, hotels, factories, public places, and more. With the development of video surveillance technology, it has the following characteristics: the scale and radiation area are getting bigger and bigger: some cities have tens of thousands of cameras; the monitoring period is getting longer and longer: 7x24 hours without interruption, retention period from 1 week to 1 month 3 months or even longer; the definition requirements are getting higher and higher: the resolution is improved from 352x288 to 704x576, and the code rate is from 300Kbps to 2Mbps. This requires the corresponding storage system to have hundreds of terabytes or even petabytes of data storage capacity, to have enterprise-level stability, to ensure uninterrupted 7x24 hours of business, and to be cost-effective and low-cost.。