I think I've *discounted* IDE as a potential problem: $ rm /tmp/test1.img $ truncate -s1G /tmp/test1.img $ guestfish <<EOF set-attach-method appliance add-drive-opts /tmp/test1.img iface:ide readonly:true run mount /dev/sda / EOF libguestfs: error: mount: /dev/sda on / (options: ''): mount: wrong fs type, bad option, bad superblock on /dev/sda, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so (the expected error) vs: $ guestfish <<EOF set-attach-method appliance add-drive-opts /tmp/test1.img iface:ide readonly:true run mkfs ext2 /dev/sda mount /dev/sda / EOF (no error) Also tried: - Adding name:vda - Running isoinfo-device before the mount. - Running vfs-type before the mount. I still couldn't reproduce this. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW