Data storage is the place in a computer where all forms of data is stored in an optical or electromagnetic form. Data storage describes all those devices, which are connected to the system via I/O (input/output) operations. Devices like hard disk and tape systems don’t use in-computer storage or computer memory. Enterprise data storage can be classified into primary storage and secondary storage, depending upon the use of data and media it is placed on.
The Primary storage stores data on in-built devices, such as RAM and the processor's L1 cache. Secondary storage includes all those data which are stored on tapes, hard disks and other devices using the I/O operation. Secondary storage media is quite popular in cloud storage. While primary storage is faster to access, secondary storage can accommodate more data.
Network Attached Storage (NAS) is a computer data storage server, which is attached to a computer network. The file-level server provides data access to a diverse group of clients. It consists of one or many storage drives, which are arranged in redundant storage containers (RAID). It is a specialized computer, which is designed to act as a purpose-built server and helps in sharing files over the network. NAS acts as both, file system and storage system. This feature makes it a better option than SAN (Storage Area Network), which offers just block-based storage.
NAS devices can be broadly divided into three categories – Computer-Based NAS, ASIC based NAS, and Embedded System Based NAS. Along with providing the centralized storage to client computers, NAS also helps lower-cost systems, such as, fault-tolerant and load-balancing emails, and web server systems.