Which of the following refers to a digital storage system directly attached to a server or workstation,
without a storage network in between?
A.
DAS
B.
SAS
C.
NAS
D.
SAN
Explanation:
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.C is incorrect. 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.B is incorrect. 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.D is incorrect. 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.