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There are many things that can make a difference in this case.
- What size can be copied and what size cannot be copied? Where is the limit?
- What computer is it
Brand name and model
- What version and flavour of Ubuntu are you running live?
- What are the source disk and target disk?
- What are the source partition and target partition?
Connect the target drive and mount it! Please post the output of the following three commands in a terminal window!
You can copy and paste the text from the terminal window to the editing windows (for a reply). Select Advanced, mark the text and click on the # icon above the editing window to put the text within code tags
sudo parted -l # ... space minus ell