A while ago I thought it would be a good idea to make a backup of my Linux server by just dumping the complete disk to a file. In retrospect, it would have been much easier had I just dumped the individual filesystems.
When I finally got around to using this backup, long after the 10GB disk had perished I realized that to use the loopback device to mount a filesystem it actually needs a filesystem to mount. What I had was a disk image, including partition table and individual partitions. To further complicate matters the data partition was also not the first partition inside this image.