It sounds like your disk has gone AWOL. Copyutil will do a sequential read from the disk, and it sounds like it will not pass beyond a disk read error.
One of your responses said this was a non-root disk (partition) - if so, you should be able to boot into single user mode, but this won't do you any good unless you know the internal details of the filesystem. Basically, you're very likely to have lost the data unless you already have a backup.
One extremely outside possibility - attach the disk to a working system, then use dd to copy the problem disk to a spare disk of the same type - you may have to skip around bad blocks. This will give you a replica of the good bits of the disk, then you can try doing fsck on the copy, avoiding the media errors for the bad bits on the original. Of course, if the bad bits include the free list, or the inode table, or the indirect blocks, fsck may complain, abort, or even destroy the underlying data.
