Label: SAN NAS This article refers to the address: http:// Storage development and common technologies: In the late 1990s, digital video processing (DSP)-based digital video surveillance began to become popular. Various codec technologies have been widely used in image processing. The processed images can also be digital code streams. The way to transmit, the storage of images also begins to enter the digital period. The most typical application is a digital hard disk recorder (DVR), which uses an internal hard disk for image storage. This type of storage has fundamentally changed in terms of save time, image retrieval, system maintenance, and remote calls. However, since most of the digital video surveillance systems at this stage have obvious localization features and relatively small scale, the storage also exhibits obvious front-end and stand-alone features. In recent years, with the rapid development of information network technology, networked video surveillance systems with centralized management and control through the central service platform and network video server and IPCamera as the front-end have begun to be widely deployed. Due to the reasonable architecture, flexible expansion and clear hierarchy, network video surveillance can bring users a new security application experience, which quickly becomes the main form of building a new generation video surveillance system. The distributed front-end and platform architecture, centralized management and control, and flexible and convenient user access make the storage part of the network video surveillance system also begin to be networked. Networked storage brings a new storage architecture to video surveillance. On the one hand, users are more flexible in storage deployment and easier to access. On the other hand, it is more convenient to build a video surveillance system that requires large-capacity storage. DVR storage: codec internal storage - DVR storage is currently the most common storage mode, the codec device directly mounts the hard disk, and currently can carry up to 8 hard disks. However, due to the limitation of the performance of the codec device, the hard disk sequential write mode is generally adopted, and the RAID redundancy technology is not applied to implement data protection. As the capacity of hard disks continues to increase, the probability of loss of critical data in a single hard disk drive increases synchronously, and the limitations of DVR performance also affect the sharing and analysis of image data. The characteristics of this method are: cheap, easy to use, can be operated by remote control and keyboard; DVR mode is suitable for small-scale, distributed deployment. Domestic DVR products such as Haikang and Dahua's products are already very mature. Codec + storage: Codec plug-in storage device, connected through the external storage interface of the codec, mainly using storage protocols such as SATA, USB, iSCSI and NAS. This method can realize the re-expansion of the codec capacity, which is suitable for small and medium-sized deployment. The monitoring video data is guaranteed by the RAID technology in reliability. Among them, the SATA/USB mode adopts the direct connection mode, which cannot be shared and has low expansion capability; and the IP network (iSCSI and NAS) mode has better expansion capability and sharing capability. Haikang's DS series monitors NAS storage products, and Bunnon's SMI series storage products are mature in the monitoring industry. Centralized storage: The server connects to the front-end codec, downloads data through the streaming protocol, and then stores it on the storage device. The server and storage device can be connected through SCSI, iSCSI, NAS, and FC protocols. Centralized storage is suitable for deployment of large and medium-sized platforms. In the centralized storage mode, the IP connection mode (iSCSI, NAS) has good scalability and manageability, and has a high performance price ratio. Monitoring storage three patterns First, the front-end storage pattern The so-called front-end storage is a built-in storage component in the front-end device of the network video surveillance system (such as a network video encoder or a network camera), and the front-end device directly performs local recording and storage of the monitoring image. Front-end storage has several advantages: First, it can reduce the capacity pressure caused by centralized storage through distributed storage deployment; Second, it can effectively alleviate the pressure of network traffic brought by centralized storage; Third, it can avoid centralized storage in Loss of image when the network fails. For front-end storage, since a single front-end encoding device usually has a small number of monitoring points and a long storage time, the storage capacity is not high. The network camera generally uses a CF card or an SD card, and the video server generally uses a built-in hard disk. This is basically the same as previous stand-alone storage. In essence, unlike the previous stand-alone storage, in order to ensure the flexibility and convenience of user access, all front-end storage in the network video surveillance system must be able to provide peer-to-peer access, but also through a unified interface. Centralized sharing of all content. To this end, the network video surveillance system centrally manages and schedules all front-end storage through the central service platform, and realizes the networking of storage space and storage content. In this way, the user can directly log in to a single front-end device for on-demand playback of video data, or can centrally log in to the central service platform for centralized retrieval and playback of all front-end video data. Second, the central storage pattern In the network video surveillance system, more central deployment is deployed. The front-end device collects the monitoring point image and encodes the compression into a digital monitoring code stream, and then transmits the data to the central service platform through the network, and the central service platform distributes the code stream to the network recording unit for centralized storage. In many large-scale video surveillance networking applications, multi-level distributed central storage, that is, sub-center storage, can also be used, which can reduce the storage capacity and network traffic pressure brought by centralized storage of a central point. Greatly improve the reliability of the system. The use of center/sub-center storage has obvious advantages in the following aspects: First, it is more convenient for users to retrieve and recall video resources; second, the integrity of stored content is easier to guarantee, not because of a front-end device. Theft or damage leads to the loss of important content; the third is that resource scheduling can be reasonably performed to allocate storage space for the front-end equipment on demand, thereby saving resources; fourthly, it is conducive to formulating diverse storage strategies to meet the individual needs of users. The fifth is easy to maintain, easy to focus on detection and timely troubleshooting. For applications with fewer monitoring points and less storage time, the central/sub-center storage can be deployed in a relatively simple way, such as DAS (Direct Access Storage), with a server plug-in hard disk or an external disk cabinet. Single machine is similar. With the wide recognition of the advantages of network video surveillance, more and more large-scale and even large-scale video surveillance systems are beginning to appear. For example, the social security monitoring system in the construction of “Safe Cityâ€, China Telecom and China Netcom are fully promoting. The two major operational-grade video surveillance systems, the “global eye†and the “wide-visionâ€, are faced with the need for large-scale access and large-capacity centralized storage of front-end equipment. In the past, the single-machine storage method could not meet the application requirements of these systems for flexible capacity expansion. More advanced network storage devices and storage technologies must be adopted, and typical ones are SAN, NAS and iSCSI. SAN (Storage Area Network) originated in the mid-to-late 1990s. Unlike DAS, SAN is based on Fibre Channel technology. Servers and storage arrays are connected by Fibre Channel switches to form a regional network dedicated to data storage. The SAN adopts a network-oriented storage structure, which separates data processing and data storage. It has the characteristics of easy storage expansion, flexible addressing, long-distance data transmission, high I/O performance, and high utilization of storage devices. It is a brand new Storage architecture. Unlike SAN-based proprietary Fibre Channel protocols, NAS (Network Access Storage) implements the interconnection of servers and storage arrays based on IP networks, communicates using TCP/IP protocols, and transfers data in file-level I/O. In contrast, the installation, commissioning, use, and management of NAS devices is simpler and the deployment costs are relatively low. iSCSI is a new standard protocol of IETF, which is a transmission standard for converting SCSI block data into network packets through IP network. It transmits data through IP network like NAS, but in data access mode. , the same as the NAS, and the same BlockProtocol protocol as the SAN. Therefore, the value that iSCSI brings to users is: First, iSCSI makes it possible to transmit SCSI packets over Ethernet, freeing the SAN from expensive fiber-optic networks, and achieving the original functions through IP networks, reducing both. Management complexity reduces costs. Second, due to the complexity of user application requirements, both SAN and NAS storage networks are deployed at the same time, while iSCSI can combine the two. These features of iSCSI are very suitable for the current status and direction of video surveillance development, especially in the field of carrier-grade video surveillance. The storage scale is large and the investment is high. Based on the mature IP network, the central/sub-center storage system is built. iSCSI Technology is undoubtedly a good reference. Third, the application storage pattern The storage network architectures commonly used in video surveillance systems are DAS, NAS, SAN, and IP-SAN. The types of storage devices commonly used are SCSI disk arrays, FC, and iSCSI devices. These devices are mature in technology, simple in structure, and easy to install and implement. However, these devices have a common disadvantage. The storage device can only play a simple data storage function in the video surveillance system, and cannot replace the server to run specific application software. The video surveillance system still needs a large number of dedicated servers. In fact, with the rapid development of chip technology, the computing and processing speed of CPU or dedicated ASIC chips has doubled, while the overall price of storage devices has been decreasing. When selecting and purchasing equipment, users generally choose a slightly higher level of storage equipment for the sake of device replacement. Moreover, when the investment is abundant, the price difference has a smaller impact on the user. Therefore, in many application systems, the performance of storage devices purchased by users is often higher than the actual needs of actual business systems, and even exceeds several times. In some small and medium video surveillance systems, performance bottlenecks in the system often appear on the video server rather than the storage device. The bandwidth that the storage device can provide is often twice or three times the actual total bandwidth of video surveillance. IOPS is also the actual demand. 3 to 5 times. The storage device controller is in a semi-loaded state for a long time, and a large amount of high-performance resources are wasted. In order to ensure high availability, high efficiency, stability and security, the controller part of the storage device is generally designed and uses a dedicated processor and cache, and its technical parameters and performance are higher than ordinary PC servers. In order to effectively utilize the redundant resources of the storage, special application software can be embedded in the controller of the storage device. The storage device not only provides a data storage server for the system, but also provides a certain software application server, and the storage device is called Application storage. Tinned Copper Clad Aluminum TCCA Copper Clad Aluminum Tinned Wire,Tinned Copper Clad Aluminum Audio Cable,Tinned Copper Clad Aluminum Alloy Wire ,Copper Clad Aluminum Tin Plating changzhou yuzisenhan electronic co.,ltd , https://www.ccs-yzsh.com