Okay hoping someone can throw in some ideas.

I needed to reformat a 120GB USB Maxtor HD so it has GUID partition, however it has stuff on it, and I am temporally short of space. I know my mums MacBook has some free space, and I was having to visit her anyway.

So I get there and set up her MacBook to copy file across into 'hold' folder, no problems, around 45 minutes, create a GUID partition and then start to copy file back.

The process seems to be going fine, then a error message pops up, and the copy back has failed, not enough info to tell if the problem was the source (MacBook) or the destination (Maxtor HD) so I try another attempt doing it in a different order, yet grief again later.

At this point I am desperate, and start to make a disk image, using Disk Utility, of the contents left from the 'hold' folder, and have the image saved to the Maxtor HD.

3 bloody hours later, and my mum getting very sick of me, and not having access to her MacBook, another error from Disk Utility that the process has failed! Again not enough to work out what to problem is.

So resigned to the fact that my files from the Maxtor HD are going to have to stay safe on my mums MacBook, I left feeling pretty unhappy with Apple and how neither the Finder nor Disk Utility tell you which is the problem, the source (MacBook) or the destination (Maxtor HD)

Back home I run Disk Utility again and zero format the Maxtor HD.

Guess what? No issue, no error in the process.

So what does this mean?

The Disk Utility zero format has mapped out some bad blocks? (Where does it say this happens if so? Where is the bad block mapped out info?)

Or my Mum's MacBook has a problem internal HD in it now? (How come I could copy to it and not back out???)

I know more tests can be done, but anyway thought I would ask the above, and also say how I am pissed off with Apple for not making a O.S. and utilities that cannot report better than a generic I/O error

What method do you use to transfer? WIFI, Firewire or USB?
Whichever method, try one of the alternatives.
Also how about burning the files to DVDs and at least having a secure archive of the most important files?
You don't mention the total size of the files. Perhaps breaking them down to small chunks would help.
Sorry to say, I don't know anything about GUID partitioning, so cannot comment on that side.
At a guess, I'd say you were originally HFS and your mother's MB is also HFS and the only change you've made is going to GUID on your Intel machine. Perhaps some of the Mactalkers more experienced with GUID partitioning may comment.

What's built into the Maxtor HD, USB only.

Can't. See above.

Can't. See below... (No single file is more or less important than any other.)

Around 50GBs.

Tried in the copy process, did not help at all.

The Maxtor HD was originally HFS and my mother's MB is GUID as all Mactel units should be.

My Intel machine was not even there

Yes the only change I made was the Maxtor HD from Apple Partition Map, which has nothing to do with HFS, to GUID HFS.

So is there a suggestion that you can't copy files from Partition scheme to another?

How come I could go from Maxtor HD with HFS Apple Partition Map to HFS GUID on my mums MacBook at the start then?

BTW The error code for the failed copy is -36 ioErr I/O error.

Also I have done one additional test, or mum has, and the error is on her MacBook.

So no issue with the Maxtor HD.

So a problem with the MacBook HD by the looks of it.

But the S.M.A.R.T. status : Verified.

I am sorry SyncMan. I'm no help at all. Just reread your first post and had skipped the USB Maxtor HD (which I now understand to be external).
I also have an external USB drive, which I use for backups daily. It tends to be very touchy and often spat the dummy until I changed cables.
Next peculiarity was that it has to be plugged in AFTER start up to run without error.
Also was necessary to ALWAYS use File>Eject before shutting down.
All my other USB connections remain constantly plugged in and work just fine.
I know of no reason why partitions would be sensitive to files, it was just a thought, looking for some difference that may have caused your situation.
Many years ago, there was a directory of error codes. Maybe Google? Though yours (-36 ioErr I/O error) looks like a straightforward On/Off and that points to the connection or cable.
Hope someone else has a solution for you.

Was it a bus-powered notebook size external drive or full-size powered external? Bus-powered drives can sometimes be flakey.

Okay, sorry, I don't think I explained my update before well enough.

The update is that I have reduced the fault down to my mums MacBook.

She is not happy

If I take one the of the files that I copied across and duplicate on the internal MacBook HD, it fails to duplicate (copy), and gives the I/O error -36.

So it looks like bad sectors on my mums internal MacBook HD.

What do you do about them?

If they are critical files , I wouldn't use USB full stop. Firewire is a much more robust interface . You only have to do a search here on this forum and on others to see the problems Mac users have encountered with file transfer over USB that have magically disappeared once the user switched to Firewire .
Of course not all of it is USB's fault but partly the way Apple has implemented it.
You should also initiate an incremental backup strategy rather than relying on just one HD for all your backup files.
I would take some of the suggestions above on board and at least burn your data to DVD's or to possibly another external HD ( FW of course ).

You could take a stuffed HD and write to it but you won't be able to read/write from it. I know from bitter experience.
Run a simple test from TTPro or DW or even DU as preventative maintenance on any drive you are backing up to BEFORE you write the data to it.
SMART is also not always going to throw up any errors with the HD. You need a heavier duty utility like the above to really test it.
All this of course is after the event and no good to you in your present pickle.
Do you have an another external drive you can use or burning some DVD's from your Mums MB once you recover the data ?

Stewie

Edit : Here is some tech speak from Apple on GUID that may point you in the right direction.
http://developer.apple.com/technotes/tn2006/tn2166.html

I am not sure what to say to that? How can I make a USB only Maxtor HD purchased from Officeworks use Firewire?

I would if they had the port anywhere on the drive

Trying to sort something out on that front.

Thanks.

For your information

http://www.wisegeek.com/what-is-a-fi...sb-adapter.htm