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(computer science)
The tendency of files in disk storage to be divided up into many small areas scattered around the disk.
(cell and molecular biology)
Amitotic division; a type of asexual reproduction.
(mining engineering)
The blasting of coal, ore, or rock into pieces small enough to load, handle, and transport without the need for hand-breaking or secondary blasting.
Disordered behavior and mental processes.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.




The process, or result, of splitting a large area of free memory (on disk or in main memory) into smaller non-contiguous blocks. This happens after many blocks have been allocated and freed. For example, if there is 3 kilobytes of free space and two 1k blocks are allocated and then the first one (at the lowest address) is freed, then there will be 2k of free space split between the two 1k blocks. The maximum size block that could then be allocated would be 1k, even though there was 2k free. The solution is to "compact" the free space by moving the allocated blocks to one end (and thus the free space to the other).

As modern file systems are used and files are deleted and created, the total free space becomes split into smaller non-contiguous blocks (composed of "clusters" or "sectors" or some other unit of allocation). Eventually new files being created, and old files being extended, cannot be stored each in a single contiguous block but become scattered across the file system. This degrades performance as multiple seek operations are required to access a single fragmented file.

Defragmenting consolidates each existing file and the free space into a continuous group of sectors. Access speed will be improved due to reduced seeking.

The rate of fragmentation depends on the algorithm used to allocate space and the number and position of free sectors. A nearly-full file system will fragment more quickly.

MS-DOS and Microsoft Windows use the simplest algorithm to allocate free clusters and so fragmentation occurs quickly. A disk should be defragmented before fragmentation reaches 10%.

See garbage collection.
This article is provided by FOLDOC - Free Online Dictionary of Computing (


(1) See Android fragmentation.

(2) Storing data in non-contiguous areas on disk. As files are updated, new data are stored in available free space, which may not be contiguous. Fragmented files cause extra head movement, slowing disk accesses. A defragger program is used to rewrite and reorder all the files.

(3) In an IP network, breaking a data packet into smaller pieces in order to accommodate the maximum transmission unit of the network. See IP fragmentation.
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References in periodicals archive ?
Our results showed an increased rate of DNA fragmentation in infertile men compared to control men, not with age.
As can be seen from Table 1, by doubling the borehole size and scaling the blast dimensions, or the other controllable variables, proportionally the fragmentation size significantly increases.
Figure 24 shows the simulation results obtained for different values of RTS and fragmentation thresholds.
Thus, [H.sub.w] was mainly determined by rock fragmentation and rotational cutting.
Identifying how forest fragmentation alters the distribution of different psittacid species is essential for the implementation of measures that are effective in mitigating its consequences.
There are not many studies conducted related to land fragmentation in the country in general and ANRS in particular at different levels.
Grade 2--More than 2 but less than 10 foci with elastic lamellae fragmentation in one microscopic field.
There are some reasons to do the fragmentation of the database in distributed systems [OV95]:
* Set the fragmentation thresholds for reorganize and rebuild jobs
The author has organized the thirteen chapters that make up the main bulk of his text in five parts devoted to unity of method, language, laws, and objects; evidence of fragmentation in the field; historical unification attempts; the fragmentation of clinical psychology; and psychology as science and profession.
The report, requested by current and former Republican members of the House of Representatives' House Financial Services Committee, was intended to review the financial regulatory structure and any related impacts of fragmentation or overlap, and to provide suggestions to Congress to alleviate certain fragmentation and overlap by federal agencies overseeing depository institutions, among others.
To address this problem and to avoid this fragmentation, he proposed the unification of the studies; based on this premise, he wrote his famous book, Ihya al Ulum ad-Din (The Unification of Religious Studies).