e to separate SANs is the use of hard drives on commodity servers to store databases and other files. Storage on commodity servers was pioneered by Google for its cloud offering. It involves the use of sophisticated software to keep track of and identify files stored on the servers. The software applies a unique identifier to each file, which it transmits to the application SO that it can be accessed. Because of its cost savings, other cloud providers, including Amazon, use this lower-cost storage method rather than traditional SANs. Protocols for Communications in LANs All devices connected to LANs use network protocols to access them and to reach other devices and applications, which might be located on the same floor, on another floor, in another building, or even on another continent. By providing a uniform way to communicate, they simplify the process of linking devices, applications, and networks together. Ethernet and TCP/IP are the most common of these protocols. Fibre Channel is used in SANs. The Ethernet Open Standard for Network Access Ethernet is an 802.3 open-standard protocol, approved by the Institute of Electrical and Electronics Engineers (IEEE), a non-profit standards body. Devices such as personal computers and printers use it to access the LAN and to retrieve packets from wired and wireless LANs. Each device on an Ethernet LAN has an address, referred to as its Media Access Control (MAC) address. Switches use the MAC address to send mes- sages to LAN-attached devices. Ethernet is the first LAN access scheme that was widely adopted. Because it is based on an open standard, it is broadly available to different manufacturers. In the 1980s, departments within companies began to use Ethernet to link their computers together over coaxial cables to share software applications, such as accounting and financial tracking packages as well as printers. The use of the lighter-weight, lower- cost unshielded, twisted-pair (UTP) cabling occurred following the 1990 adoption of new UTP cable standards on LANs. 