Computer data storage, often called storage or memory, is a technology consisting of computer components and recording media used to retain digital data. It is a core function and fundamental component of computers
The term storage management encompasses the technologies and processes organizations use to maximize or improve the performance of their data storage resources. It's a broad category that includes virtualization, replication, mirroring, security, compression, traffic analysis, process automation, storage provisioning and related techniques.
By some estimates, the amount of digital information stored in the world's computer systems is doubling every year. As a result, organizations feel constant pressure to expand their storage capacity. However, doubling a company's storage capacity every year is an expensive proposition. In order to reduce some of those costs and improve the capabilities and security of their storage solutions, organizations turn to a variety of storage management solutions.
Storage Area Network (SAN)
A storage area network (SAN) is a dedicated high-speed network (or subnetwork) that interconnects and presents shared pools of storage devices to multiple servers.
A SAN moves storage resources off the common user network and reorganizes them into an independent, high-performance network. This allows each server to access shared storage as if it were a drive directly attached to the server. When a host wants to access a storage device on the SAN, it sends out a block-based access request for the storage device.
A storage area network is typically assembled using three principle components: cabling, host bus adapters (HBAs) and switches. Each switch and storage system on the SAN must be interconnected and the physical interconnections must support bandwidth levels that can adequately handle peak data activities.
Storage area networks are managed centrally and Fibre Channel SANs have the reputation of being expensive, complex and difficult to manage. The emergence of iSCSI has reduced these challenges by encapsulating SCSI commands into IP packets for transmission over an Ethernet connection, rather than a Fibre Channel connection. Instead of learning, building and managing two networks -- an Ethernet local area network (LAN) for user communication and a Fibre Channel SAN for storage -- an organization can now use its existing knowledge and infrastructure for both LANs and SANs
Network-Attached Storage (SAN)
Network-attached storage is a type of dedicated file storage device that provides local area network (LAN) users with centralized, consolidated disk storage through a standard Ethernet connection
NAS devices are connected to the LAN as an independent network device and assigned an IP address. The primary advantage of NAS devices is that network storage is no longer limited to the storage capacity of a computing device or the number of disks in a local server. Many NAS products can hold enough disks to support RAID, and multiple NAS appliances can be attached to the network for storage expansion.
NAS devices typically do not have a keyboard or display and are configured through a web-based management utility. Some NAS boxes run a standard operating system (OS) like Microsoft Windows, while others may run their own proprietary operating systems. Although Internet Protocol (IP) is the most common network protocol, some NAS products may support other network protocols such as Network File System (NFS), Internetwork Packet Exchange (IPX), NetBIOS Extended User Interface (NetBEUI) or Common Internet File System (CIFS), an enhanced version of the Microsoft open, cross-platform Server Message Block (SMB) protocol. Some NAS products also support Gigabit Ethernet (GigE) for faster data transfers across the network.
NAS products are often categorized as being enterprise, mid-market or desktop. Such categorizations are usually based on the NAS device's number of drives, its drive support, its drive capacity and its scalability.