Few people will dispute the impact of hard drive storage on video recording. Few technologies can present such a paradigm shift to an industry as did the switch from VHS tapes to digital recording on computer hard drives. The shift continues today as the need to store vast amounts of video data drives the expansion of data storage beyond the capacity of a single hardware device. Several options exist for storing large amounts of data and the selection of the best one depends upon the video recording platform, storage connectivity and last but not least the requirements of a customer's IT department.
Storage can be defined as Direct Attached Storage; Network Attached Storage; Storage Area Network; or the latest arrival--Edge Storage. Each of these has unique-and when applied correctly-powerful benefits.
Direct Attached Storage (DAS) is the kind of storage that everyone has known since the early days of PCs. Simply put, the hard disk drive is connected to the computer's motherboard via a direct electrical connection. Over time, the interface changed and in the case of server class machines, frequently became an array of multiple disk drives configured to provide a level of redundancy and fault tolerance. These arrays are commonly known by the type of redundancy which is defined by the RAID number.
Network Attached Storage (NAS) provides storage capacity by connecting the storage device directly to the data LAN. In effect the NAS is simply a device on the network, with its own IP address. NAS allows servers with different operating systems-Windows XXXX or UNIX or Linux to access the storage capacity. Management of NAS provides enhanced security as well as a defined data back-up strategy. Expandability is also a significant benefit of NAS. If the NAS device reaches capacity another NAS can be added to the network to increase storage capacity. Unfortunately, along with the benefits there is a significant downside to a NAS. Overall, network traffic is increased by the use of NAS. All data written to the NAS must be considered in the network bandwidth calculations and can present a considerable load.
Storage Area Network (SAN) is similar to a NAS in that it is an independent device on the network which can be addressed from multiple devices. Significant in the difference is the use of a separate network for the storage data traffic. The separate network provides for storage management, system backups and redundancy of data without consuming bandwidth on the production IT network. Since a SAN is frequently located physically close to servers it supports, high bandwidth is more easily achieved. Typically, the network connections to a SAN are significantly higher speed than the normal 100 Mb or 1 GB network. This is accomplished by specialized network electronics referred to as host bus adapters (HBA). Connectivity is often accomplished with specialized physical layer known as Fibre Channel which can achieve 10 Gb or higher bandwidth. IP networks also support SAN architecture with a protocol known as iSCSI. While iSCSI is typically slower than Fibre Channel the benefit is the ability to carry storage data over long distances. This factor supports SAN being used as a part of a disaster recovery strategy. Large IT organizations frequently have very large SAN configurations. It is not unusual to have SAN capacity in the petabyte range - 1 PB = 1000 TB.
Edge Storage is a technique to provide storage capability at the camera. In some cases this is used as a "network failure" strategy while in others it is used as a means of managing network bandwidth. In the case of the "network failure" strategy, the local storage is only used when the camera detects a failure to communicate with the server that is actively storing the camera data. Typically these storage functions are managed by the use of a flash memory (SD) card similar to those used in digital cameras. The bandwidth management strategy offers the capability for the camera to record and hold a limited amount of video data on a local hard drive that is a component of the camera. Through local storage the camera can apply video analytics to the data and send only the video that violates the analytics rules and thus reduce the amount of network traffic. All video can be maintained at the camera location for a limited period for viewing and recovery if an incident occurs.