Having just installed a new hard disk, I have been copying the data from the old server it will replace.

I mounted the old hard disk (via nfs using no_root_squash) and used 'cp -rp /mnt_from/* /destination ' (as root) and left it for the night...

To my horror , the next morning I found that many of the files had not been copied although some (in no apparent order) had been.

Copying directories individually seems to be fine and the total amount to copy is about 80 Gig (just 'normal' files and links)

Distro is Debian Woody (all updated) and no error messages were reported.

Any suggestions as to why I should get this behaviour?

I assume there is something I don't know about cp but it is just a little unnerving not to mention time consuming

It might be a permission problem or could be caused by trying to copy from a running system; it's going to try and copy your /proc files and everything else which could cause problems. If you have the disk space, the easiest solution is to use some partition imaging software like partimage to copy over the entire partition(s) to your new drive. You'll have to have the space to store the images in a separate partition, slave the new hard drive to the old and restore the images to the new drive. Here's a link on linux imaging software:

http://www.desktop-linux.net/backups.htm

It won't include /proc etc, as it is only certain exported directories (a whole partition, in fact) being copied ... I suppose it could be usage but with only 5 users (all logged out) I had hoped not, although you never know who has forgotten to do what.

Thanks for the link into imaging software - it might be useful if I get back on Monday and it still hasn't copied (god, I hope not...) and certainly worth noting for the future.

Try using the cpio command. I did find it best to boot up with a rescue cdrom and run the following steps....

Note: your partition locations may be different

mkdir /mnt/new /mnt/old

mount /dev/hda1 /mnt/old
mount /dev/hdb1 /mnt/new

change to /mnt/old and get to the top. Then run cpio from there...

find . -depth | cpio --pass-through \
--preserve-modification-time \
--make-directories --verbose /mnt/new