Posted by Arowosegbe Olawale in General

The need for efficient and low-cost storage in IP-based systems has had a major impact on the development of modern CCTV systems. IP-based systems and hybrid systems, which combine analogue and IP technology and communications protocols, can choose from a variety of network storage options on the market. Most businesses that invest in a sizable CCTV system will need more space than what their DVRs can provide and will turn to the network for their video archives. The storage media in a networked system are typically located in a location remote from the client computer. Network storage, on the other hand, is decoupled from the recording device and therefore more scalable to meet the massive storage needs associated with video images.

5.2.1 Interface Protocols

The small computer systems interface (SCSI) protocol is commonly used to link servers to mass storage devices. SCSI is widely used as a storage interface for CCTV systems. The iSCSI protocol has been updated to include the ability to access voice, video, and data from various types of network storage devices and make it available across an IP network in response to the proliferation of IP technologies and the demand for interoperable and open architecture. SCSI storage capabilities are combined with those of the transmission control protocol/internet protocol (TCP/IP) in iSCSI. The I in iSCSI stands for the Internet. Direct-attached storage, storage area network, and network-attached storage are all types of network storage devices. 

5.2.2 Direct Attached Storage

Direct Attached Storage (DAS) is an older technology that was originally designed as an independent method of linking hosts to storage devices via a straightforward SCSI connection. When a DAS system adds storage and servers to meet demand, it can lead to an increase in the number of separate server and storage islands. Due to its intrinsic connection to the servers, storage sharing is constrained in a DAS setup. CCTV systems still make use of DAS, but these days it's more common for the video feeds to be stored offsite. Server attached storage (SAS) was created as an alternative to DAS as LANs became more commonplace, with the goal of implementing a distributed method through a centralized network.

5.2.3 Storage Area Network

A SAN is comprised of communications infrastructure and management layers that guarantee the security and reliability of data transfer. The storage devices in the SAN store data blocks. When necessary, operators access the data blocks via the network. As depicted in Figure 5-1, a SAN is a dedicated, high-performance network that typically employs fibre channel technology. Fiber channel protocol and interconnect technology facilitate high-performance block data transfers.

In general, SANs are structured in various ways to connect multiple storage devices, such as DVRs and NVRs, to one or more centralized, shared storage systems. More CCTV components are being designed to connect directly to SANs via iSCSI.

Here are examples of SAN Architecture for CCTV systems: 

Figure 5-1. Storage Area Network

Figure 5-2. Storage Area Network

Note: 

The first example: Figure 5-1. Storage Area Network -  shows an example of a linear SAN. The IP Cameras are directly connected to the Network Switch, and Switch connected to the Multiple NVRs, the NVRs connected to Storage Switch and Storage Area Network.

The second example: Figure 5-2. Storage Area Network -  shows an example of a central SAN, where the switch is centralized and connected to all parts of the component.