Browse Definitions :
Definition

Digital Data Storage (DDS, DDS-1, DDS-2, DDS-3, DDS-4)

Digital Data Storage (DDS) is a format for storing and backing up computer data on tape that evolved from the Digital Audio Tape (DAT) technology. DAT was created for CD-quality audio recording. In 1989, Sony and Hewlett Packard defined the DDS format for data storage using DAT tape cartridges. Tapes conforming to the DDS format can be played by either DAT or DDS tape drives. However, DDS tape drives cannot play DAT tapes since they can't pick up the audio on the DAT tape.

DDS uses a 4-mm tape. A DDS tape drive uses helical scanning for recording, the same process used by a video recorder (VCR). There are two read heads and two write heads. The read heads verify the data that has been written (recorded). If errors are present, the write heads rewrite the data. When restoring a backed-up file, the restoring software reads the directory of files located at the beginning of the tape, winds the tape to the location of the file, verifies the file, and writes the file onto the hard drive. DDS cannot update a backed-up file in the same place it was originally recorded. In general, DDS requires special software for managing the storage and retrieval of data from DDS tape drives.

There are four types of DDS drives:

  • DDS-1: Stores up to 2 gigabytes of uncompressed data on a 120-minute cartridge.
  • DDS-2: Stores up to 8 GB of data in compressed format on a 120-minute cartridge. DDS-2 is ideal for small network servers.
  • DDS-3: Stores up to 24 GB of data on a 125-minute cartridge. The DDS-3 drive is ideal for medium-sized servers. DDS-3 uses PRML (Partial Response Maximum Likelihood). PRML eliminates electronic noise for a cleaner data recording.
  • DDS-4: The newest DDS drive, DDS-4 stores up to 40 GB of data on a 125-minute cartridge. Small to mid-size businesses benefit from the DDS-4 drive.

A DDS cartridge needs to be retired after 2,000 passes or 100 full backups. You should clean your DDS tape drive every 24 hours with a cleaning cartridge and discard the cleaning cartridge after 30 cleanings. DDS tapes have an expected life of at least 10 years.

This was last updated in April 2005

Continue Reading About Digital Data Storage (DDS, DDS-1, DDS-2, DDS-3, DDS-4)

Start the conversation

Send me notifications when other members comment.

Please create a username to comment.

SearchCompliance

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

  • PCI DSS (Payment Card Industry Data Security Standard)

    The Payment Card Industry Data Security Standard (PCI DSS) is a widely accepted set of policies and procedures intended to ...

  • risk management

    Risk management is the process of identifying, assessing and controlling threats to an organization's capital and earnings.

SearchSecurity

SearchHealthIT

SearchDisasterRecovery

  • call tree

    A call tree is a layered hierarchical communication model that is used to notify specific individuals of an event and coordinate ...

  • Disaster Recovery as a Service (DRaaS)

    Disaster recovery as a service (DRaaS) is the replication and hosting of physical or virtual servers by a third party to provide ...

  • cloud disaster recovery (cloud DR)

    Cloud disaster recovery (cloud DR) is a combination of strategies and services intended to back up data, applications and other ...

SearchStorage

Close