What is DAS NAS SAN?

Difference between SAN - NAS - DAS

DAS:
Direct Attached Storage. Storage

(usually disk or tape) is directly attached
by a cable to the computer processor.
(The hard disk drive inside a PC or a
tape drive attached to a single server
are simple types of DAS.) I/O requests
(also called protocols or commands) access
devices directly.

NAS:

Network Attached

Storage. A NAS device

(“appliance”), usually an

integrated processor plus

disk storage, is attached to

a TCP/IP-based network

(LAN or WAN), and

accessed using specialized

file access/file sharing

protocols. File requests

received by a NAS are translated by the internal processor to device requests

SAN: 

Storage Area Network. Storage

resides on a dedicated network. Like DAS,

I/O requests access devices directly. Today,

most SANs use Fibre Channel media,

providing an any-to-any connection for

processors and storage on that network.

Ethernet media using an I/O protocol

called iSCSI is emerging in

NAS gateway:

A NAS

device without integrated

storage (i.e., just the

NAS processor). Instead,

the NAS device connects

externally to storage by

direct attachment or by SAN.