Which of the following refers to a digital storage system directly attached to a server or workstation, without
a storage network in between?
Direct-attached storage (DAS) refers to a digital storage system directly attached to a server or workstation,
without a storage network in between.
A typical DAS system is made of a data storage device connected directly to a computer through a host bus
adapter (HBA). Between those two points, there is no network device (like hub, switch, or router), and this is
the main characteristic of DAS. The main protocols used for DAS connections are ATA, SATA, eSATA,
SCSI, SAS, and Fibre Channel.
B: Serial Attached SCSI (SAS) is a computer bus used to move data to and from computer storage devices
such as hard drives and tape drives. SAS depends on a point-to- point serial protocol that replaces the
parallel SCSI bus technology. SAS offers backwards- compatibility with second-generation SATA drives.
C: Network Attached Storage (NAS) is the hard disk storage that is set up with its own network address
rather than being attached to the unit computer that is serving applications of a network’s workspace users.
A fully-featured operating system is not needed on a NAS device, so often a stripped-down operating
system is used. NAS provides both storage and a file system.
D: SAN stands for storage area network. It is an architecture to attach remote computer storage devices to
servers in such a way that the devices appear as locally attached to the operating system. Sharing storage
usually simplifies storage administration and adds flexibility since cables and storage devices do not have to
be physically moved to shift storage from one server to another. SANs also tend to enable more effective
disaster recovery processes.