#Idefrag linux free

For instance, a group of files normally read in a sequence (for instance, certain DLLs and other resource files accessed by a program when it starts or, the audio/visual media files in a game) can be considered fragmented if they are not in sequential order on the disk. When a file has many extents like this, access time for that file may become excessively long because of all the random seeking the disk will have to do when reading it.įragmentation is not only limited to individual files that have multiple extents on the disk.

#Idefrag linux free

Add a new block somewhere else and indicate that F has a second extent (Example (5) on the image.) Repeat this hundreds of times and the file system will have a number of small free segments scattered in many places, and some files will have multiple extents.The file could also be so large that the operation would take an undesirably long period of time. This would not be possible if the file is larger than the largest contiguous space available. Move the file F to where it can be created as one contiguous file of the new, larger size.

When F needs to be expanded, since the space immediately following it is no longer available, there are two options: (Example (3) on the image.) If another new file, G is added, and needs only four blocks, it could then occupy the space after F and before C. (Example (2) on the image.) When a new file, F, is allocated requiring six blocks of space, it can be placed into the first 6 blocks of the space formerly holding the file B and the four blocks following it will remain available. This could be time consuming if there were hundreds or thousands of files which needed to be moved, so in general the empty space is simply left there, marked in a table as available for later use, then used again as needed. (Example (1) on the image.) If file B is deleted, there are two options, leave the space for B empty and use it again later, or move all the files after B so that the empty space is at the end.

On a blank disk, all of these files will be allocated one after the other. Consider the following scenario, as shown by the image on the right:Īn otherwise blank disk has five files, A through E, each using 10 or 11 blocks of space (for this section, a block is a allocation unit of that system, it could be 1 kB, 100 kB or 1 MB and is not any specific size).