Quantum DLT 2000 Handbook page 193

Compression. Encoding data to take up less storage space on
magnetic tape. Compression is carried out in the host (software
compression) or in the drive itself (hardware compression).
Software compression speed is dependent on host processor power,
whereas hardware compression gives optimum performance and is
transparent to the user. Data transfer speed and total tape capacity
are affected by the data compression achieved.
Compression Algorithm. A mathematical technique used to find
patterns in data and thereby save space through encoding.
Achievable compression is dependent on the type of data being
compressed. All DLTtape drives use the LZ1 compression
algorithm (See Lempel-Ziv).
Controller. The chip or circuit that translates computer data and
commands into a form suitable for use by the hard drive. Also
known as the disk controller.
Corrupted File. A data file that has been rendered unreadable due
to a variety of causes, including tampering, accidental alterations,
physical damage, and data loss. Corrupted files are one important
reason why companies need to back up on a data regular basis.
Cpio. A UNIX operating system command that stands for "copy
file archives in and out."
Cyclic Redundancy Check (CRC). See CRC.
D
DMA. Acronym for direct memory access. A process by which data
moves directly between a drive (or other device) and system
memory without passing through the CPU, thus allowing the
system to continue processing other tasks while the new data is
being retrieved.
QUANTUM DLTtape HANDBOOK G.5