There’s not much difference between moving the files to the centre of the HD or towards the periphery. The centre you see in visual representations is just that, a rectangular visual representation of your circular. Physically, the file may be anywhere on the disk.
Deleting and rewriting the file won’t help much, as the space on your disk is already fragmented. Though I have not confirmed it, OS X defragments files below 20 MB automatically. Audio and Video files tend to be large than 20 MB, and are highly fragmented.
Assuming you are talking about defragmenting the disk, I highly recommend iDefrag. I use it every 6 months, and using the computer after the defrag is like switching from an old 56k modem to Google’s fibre optics.
If you are facing a healthy file system at the level of its structure and want to find files which have disk faulty blocks, here is how I would proceed:
Make a full backup of your disk with Time Machine or Carbon Copy Cloner
Check this backup.
Run the following heavy and risky (in case you do have bad blocks outside of your filesystem structure) command (make sure the {} is quoted so filenames containing spaces work):
find / -type f -print -exec dd if="{}" of=/dev/null bs=1m \;
This heavy find command will print for any plain file its name (thus not reading it, but just its directory entry) and then continue making a full and fast read of all its data blocks.
Upon hiting the first file containing bad blocks, this find will cause the kernel to log read error on /var/log/system.log, and it will either slow down or bring your system to a total halt.
This will mostly depend on the hard drive capacity to relocate the bad blocks found on its internal pool dedicated to this usual fix task.
This file containing bad blocks will be the last name printed by find.
Write down this file name on a piece of paper!
Let's say that this file name is:
/.DocumentRevisions-V100/.cs/ChunkStorage/0/0/0/9
At this point you may have the possibility to kill find quickly by hiting ctrl+C. If killing it nicely is failing, just crash your Mac.
Upon rebooting your Mac, directly check the file containing bad blocks:
dd if='/.DocumentRevisions-V100/.cs/ChunkStorage/0/0/0/9' of=/dev/null bs=1m
If the command terminate correctly, then the error was light enough for your disk to be able to read this file and reallocate the bad blocks.
- If the command doesn't terminate, you won't be able to kill it
normally, your data is totally lost, and you will have to crash your Mac
once more.
In this last case, you have to consider replacing your disk and to work from your last backups. Some other files might also contain bad blocks and may have stayed undetected since a long time as long as you didn't read them.
The kernel won't fire a read error on a block you never read.
Best Answer
Have a look at Move files using just keyboard in Mac Finder? for a discussion of the same topic, listing a lot of options.
Assuming you are running Lion you can move files by using Cmd-C to pick them up and Cmd-Opt-V to move them to the target location.