Data storage that is connected directly to the computer accesing it
such as hard disk drives or solid state drives
connected using IDE interface or SATA interface or USB interface or SCSI interface
Can only be configured by the computer it is attached to.
It is a high-speed network that provides access to data storage at the block level.
Connects servers with storage ( disk arrays, RAID HW, tape libraries ).
Operating system view SAN devices as directly connected.
Consist of at least a) SAN switch b) Storage device c) A server.
Typically connected using Fibre Channel. Size and topology depends on business needs.