MGMT 1050 Lecture Notes - Lecture 31: Dvd Recorder, Dvd Recordable
MGMT 1050 Lecture 31 Notes – Magnetic tape
Introduction
• The inability to tamper with the data on a WORM disk has taken on importance in
business, where the permanence of many business data archives is required for legal
purposes.
• When a file is updated, it is simply written again to a new block and a new directory
entry is provided.
• Thus, a complete audit trail exists automatically.
• When the disk is filled, it is simply stored away and a new disk used.
• WORM disks work similarly to a CD or DVD.
• The major difference is that the disk is made of a material that can be blistered by a
medium-power laser.
• Initially, the entire disk is smooth.
• When data is to be written, the medium-power laser creates tiny blisters in the
appropriate locations.
• These correspond to the pits in a normal CD-ROM.
• The WORM disk is read with a separate low-power laser in the same way as a CD-ROM.
• This blister technology is used in various CD and DVD formats, called CD-R, DVD-R, and
DVD+R.
• Additionally, there are rewriteable versions of this technology.
• These are known as CD-RW, DVD-RW, DVD+RW, DVD-RAM, and DVD+RAMBD-RE.
• There are file compatibility issues between the different WORM and rewriteable CD and
DVD formats.
• Some drives will read every format
• Others will only read some of the formats.
• Magnetic tape is used by many companies for backups and archives in large computer
systems.
• Where the permanence of many business data archives is required for legal purposes.
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