DAS is the most basic level of storage. The storage devices are part of the host computer or directly connected to a single server, in which the workstation must access the server in order to connect to the storage device. On the opposite side, NAS and SAN are connected to workstation and servers over a network. In the DAS, if the server is down or experiencing problems, users can not store and access data. Surveillance images cannot be retrieved or stored. If the organization grows and needs new servers, storage for each server must be administered separately.
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NAS (Network Attached Storage):
NAS is a type of file storage device that connects to a network. NAS devices, which typically do not have a keyboard or display, provide Local Area Network (LAN) nodes with file storage through a standard Ethernet connection. In fact, NAS employs an Ethernet connection for sharing files over the network.
Each NAS on the LAN acts as an independent network node which has its own IP address. Since the NAS device has an IP address, it will be accessible over the network via that IP address. NAS devices can be built with single drive or multiple drives. The latter provides higher capacity and greater data protection.
The existence of multiple computers on the network, is a candidate for using a network attached storage (NAS) device. Some NAS servers are just used for backing up and sharing files across the network, while others can do more tasks, such as sharing a printer among the networked PCs, acting as a media streamer or even a surveillance system by supporting IP cameras.
NAS has benefits such as good reading and writing performance, good data redundancy and protection options, offering security via data encryption, sharing files, backing up data from Windows, Mac, and possibly Linux machines and offering some cloud service for storage and backup.
The application of NAS in homes is storing and serving multimedia files and automated backup. For instance, many smart TVs use NAS to provide centralized storage. If a NAS device has a server mode, it can also act as an email, multimedia, database or print server for a small business. In enterprise level, a NAS array can be used as a backup for archiving and recovery. Also, some NAS products can hold enough disks to support RAID for greater data protection.
For those systems that must store a large amount of videos/images for many days, NAS is a good option. Network-Attached Storage comprised of both hard disks and management software. NAS serves files over a network. As a result, NAS relieves the server of storage and file serving responsibilities and provides more flexibility in data access, because of its independence.