What does 'Done with volume #1' mean?
While restoring a database you might get a message like this one:
Done with volume #1, "mydb.fbk"
Press return to reopen that file, or type a new
name followed by return to open a different file.
Firebird's backup tool gbak can back up databases to a multi-volume tape backup set. When it finds a truncated backup file, it assumes that the rest of the backup is on a second tape - and waits for you to change the tape or point it to the next volume.
If you are using hard disks for backup, your backup file is most probably incomplete (maybe the backup reached the file size limit for the filesystem, see FAQ #59). Run backup with -V switch to see at which point it stops.