> O! do tell!!
>
> Mark
uhm......
[FFFFFoooooo_________] <---- let's say this is a harddrive, where:
_________ : blank space.
FFFFF, oooooo : files 1 and 2.
that drive would be in perfect state, right? all files stored neatly one
after the other and the free space is all together at the end of the
disk.
now, this:
[FFFooFoFooo_____]
this is called internal fragmentation. after a lot of
changes in file sizes, "chunks" of files get mixed up, making
a file read a slower process... file 1 and 2 are fragmented,
but the free space is still kept together.
a third situation is:
[_FFFFF___ooooooo___]
this is external fragmentation. here, the files are not
fragmented ( no internal fragmentation) however, as a consequence
of writing the files at random places on the disk, the free space
gets scattered all over. this leads, most of the times to internal
fragmentation, too. ( the next time you have to make a file you
only have scattered bits of space to write it... )
and at last.. this:
[_FoF__ooFoo_F_o__Fo]
.....this is a typical windows partition that has not beed defragged
in a long time. both internal and external fragmentation occurs, both
files and free space are a mess.
i've also seen defrag tools for the RAM in windows.. ( fragmentation is
not limited to harddrives. any modern operating system uses memory
paging or segmentation and can suffer internal and external
fragmentation in memory pages.. the same little sketches i made
would apply, but change the "file 1" and "file 2" with "process 1"
and process 2" )
Damian
PD: i like making useless explainations ;oP . sorry for a long post.
anyhow i think this stuff is useful when you want to learn about
and choose filesystems..
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