|
Cache
Specialized RAM used to optimize data transfers between
system elements with different performance characteristics.
Clean Room
An environmentally controlled dust-free assembly or
repair facility in which hard disk drives are assembled
or can be opened for internal servicing.
CD-R
An acronym for re-writable CD technology whose media
can be written to and erased approximately 1,000 times
before failure. Standard 74min CD-RW media can hold
up to 500MB when formatted for fixed-length packet writing.
CRC
Acronym for Cyclic Redundancy Check. The CRC is used
to verify data block integrity. In a typical scheme,
2 CRC bytes are added to each user data block. The 2
bytes are computed from the user data, by digital logical
chips. The mathematical model is made up of polynomials
with binary coefficients.
When reading back data, the CRC bytes are read and
compared to new CRC bytes computed from the read back
block to detect a read error. The read back error check
process is mathematically equivalent to dividing the
read block, including its CRC, by a binomial. If the
division remainder is zero, the data is error free.
Cylinder
The cylindrical surface formed by identical track numbers
on vertically stacked discs. At any location of the
head positioning arm, all tracks under all heads are
the cylinder. The cylinder number is one of the three
address components required to find a specific address.
The other two are head number and sector number.
Corrupt Data
Data that has been changed in such a way that it can
no longer be used or accessed. Data is most often corrupted
during an improper system shutdown (power or disk failure)
when good data is overwritten with random characters,
causing the data to become unreadable.
Cracker
A person who enters a target computer system without
permission. The motivation behind the trespassing may
be malicious or based on curiosity. Altruistic crackers
might notify the sysadmin of the vulnerabilities they
discover.
Cryptography
A coding method in which data is encrypted (translated
into an unreadable format) and then ecrypted (translated
back into a readable format by someone with a secret
key) using an algorithm. Cryptography is used to send
or store information securely.
Back To the Data Recovery Definitions Index |
Industry
Terms 
