Hitachi STORAGE 9900 - Manual (Page 68)

CTQ
Command-Tag Queuing.
DA
The Data Adapter resides on the CHT and connects the cache boards to the front end.
DAS
Direct Attached Storage.
Data Availability
Data availability refers to the degree to which a computer system is capable of
providing data to its users. See also Availability.
Data Copy
A term that refers to remote copy, data duplication, and data migration.
DD
Disk Director.
Data Duplication
Software that duplicates data as in remote copy or point-in-time (PiT) snapshots. Data
duplication is differentiated from data migration in that with data duplication, at the
end of the process there are two copies of data and with data migration there is only
one.
Data Migration Software
Software that migrates data from one storage device to another. This feature is different
from data duplication in that at the end of the process there is only one copy of data.
Disaster Recovery
Disaster Recovery is the profession that plans to avoid disasters and to restore services
after a disaster. It also indicates the level of preparedness to respond to an interruption
in services by implementing a disaster recovery plan to restore an organization's critical
business functions.
Downtime
A planned or unplanned interruption in system availability. Planned downtime is
usually for scheduled system maintenance and unplanned downtime usually includes
business interruptions or disasters. See also Business Interruptions, Disaster Recovery,
Business Continuity Planning (BCP), and Availability.
DR
Disaster Recovery.
Hitachi Data Sy s t e m s
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