I use "cp -a" [...] doesn't offer any assurance that the files were copied correctly. If there are disk errors (bad sectors, etc) it is possible to end up with corrupted files. I've had this happen about 10 times in the past 5 years. It was always caused by bad disks or poor connections. I always try to verify the copy before I destroy the original. That may be difficult in your case.
So instead, use "rsync -av" or even check out the checksumming options for rsync. Very powerful, good mojo.
-- Rodolfo J. Paiz rpaiz@xxxxxxxxxxxxxx http://www.simpaticus.com