Disk Fragmentation

[Tom Lawrence]

Very pleased with SuperDuper which I have used for a few weeks to clone back up my HD internal drive(363 GB of which just over 130GB is in use) to a new Lacie external drive(500 GB). I started with the full clone and then used Smart updates.

I also use TechtoolPro for maintenance and noticed that my recently defragmented internal drive has 2198 disk fragments compared to the cloned external drive of 5486. The figures for fragmented files went the other way-76 for HD and 34 for Lacie; file fragments 678 for HD and 247 for Lacie. Perhaps the latter is as a result of not cloning all files-the ones Apple suggests you do not according to SD.

Two questions please:1) Why the difference in disk fragements? and 2) What are these files that are not copied over?

[dnanian]

Not terribly surprising: data is copied file-by-file, and you'll end up with a fragmented destination. They won't match...

The files that aren't copied are things like some caches, temporary files, VM Swap files -- stuff that makes no sense to copy. The scripts, which you can view, show them all...

[Tom Lawrence]

Originally Posted by dnanian

Not terribly surprising: data is copied file-by-file, and you'll end up with a fragmented destination. They won't match...

The files that aren't copied are things like some caches, temporary files, VM Swap files -- stuff that makes no sense to copy. The scripts, which you can view, show them all...

Thanks David.

[dnanian]

Note that an erase-then-copy will defragment the destination. Not necessary, but possible.

[t3rockhall]

Originally Posted by dnanian

Note that an erase-then-copy will defragment the destination. Not necessary, but possible.

Would you have to defrag using TT4 in that case, before erase & copy? Or will erase & copy simply make a defragged backup?

TT4 can take several hours to defrag MY HD.

[dnanian]

No, you wouldn't -- an erase will make a defragged backup.