AlunFoto wrote:
2009/7/18 Bob W <[email protected]>:
I'm not sure what you mean here. Do you mean using the computer to delete
files? If so, why do you think it leaves nothing to fragment? It's not the
files that are fragmented, but the disk blocks. This may be more likely if
you use the computer because it doesn't have a 'delete all' function, so it
will always delete a file at a time. That's why many operating systems have
a defrag program.
Hmm...
When you delete files on FAT formatted media, I thought what happened
is that you overwrite the information stored in the FAT about which
disk blocks are in use. Hence if there are no files (and no
directories), no disk blocks are marked as used and you would have
nothing to defrag.
I may be wrong... :-)
Jostein
Jostein you're right. Even if there is a directory structure, if all
the files are "deleted" there's nothing to defragment.. With a Disk, a
full format will rewrite the tracks, and maybe test the surface to mark
any bad blocks, but the old data is still there. A defragment only
consolidates the actual data on the "disk" that is in allocated space.
Due to the nature of a solid state card re-writing the tracks is seen as
counter productive, and I've never seen the option to do a full format
do anything except rewrite the directory structure on any card. I was
looking into writing a program to do a real security erase on an SD or
CF card a couple of years ago, it isn't that hard to do, and unlike a
magnetic disk a single pass would be enough to completely obliterate any
residual data, but I haven't come up with anything I might want totally
removed from a card. In fact a full security erase would be more
effective with electronic media than multiple passes would be on a disk
as there would be no possible slop between tracks.
--
The free man owns himself. He can damage himself with either eating or
drinking; he can ruin himself with gambling. If he does he is certainly a damn
fool, and he might possibly be a damned soul; but if he may not, he is not a
free man any more than a dog.
--G. K. Chesterton
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