debian:~# ls -l total 0 debian:~# mkdir hda2 debian:~# mount /dev/hda2 hda2/ mount: unknown filesystem type 'ext4' debian:~# mount /dev/hda2 hda2/ -t ext3 mount: wrong fs type, bad option, bad superblock on /dev/hda2, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so debian:~# dmesg | tail -n1 [ 5293.255781] EXT3-fs: hda2: couldn't mount because of unsupported optional features (20002000). debian:~# apt-cache policy mount e2fsprogs e2fslibs mount: Installed: 2.16.1-3 Candidate: 2.16.1-3 Version table: *** 2.16.1-3 0 400 http://ftp.us.debian.org sid/main Packages 100 /var/lib/dpkg/status 2.16-3 0 400 http://ftp.us.debian.org squeeze/main Packages 2.13.1.1-1 0 500 http://ftp.us.debian.org lenny/main Packages 2.12r-19etch1 0 400 http://ftp.us.debian.org etch/main Packages e2fsprogs: Installed: 1.41.9-1 Candidate: 1.41.9-1 Version table: *** 1.41.9-1 0 400 http://ftp.us.debian.org squeeze/main Packages 400 http://ftp.us.debian.org sid/main Packages 100 /var/lib/dpkg/status 1.41.3-1 0 500 http://ftp.us.debian.org lenny/main Packages 1.39+1.40-WIP-2006.11.14+dfsg-2etch1 0 400 http://ftp.us.debian.org etch/main Packages e2fslibs: Installed: 1.41.9-1 Candidate: 1.41.9-1 Version table: *** 1.41.9-1 0 400 http://ftp.us.debian.org squeeze/main Packages 400 http://ftp.us.debian.org sid/main Packages 100 /var/lib/dpkg/status 1.41.3-1 0 500 http://ftp.us.debian.org lenny/main Packages 1.39+1.40-WIP-2006.11.14+dfsg-2etch1 0 400 http://ftp.us.debian.org etch/main Packages debian:~# uname -a Linux debian 2.6.26-2-686 #1 SMP Thu May 28 15:39:35 UTC 2009 i686 GNU/Linux debian:~# cat /etc/deb debconf.conf debian_version debian:~# cat /etc/debian_version 5.0.3 debian:~# dd if=/dev/hda2 of=hda2.img count=20000 20000+0 records in 20000+0 records out 10240000 bytes (10 MB) copied, 0.389158 s, 26.3 MB/s debian:~# file hda2.img hda2.img: Linux rev 536879105.8192 ext2 filesystem data (mounted or unclean), UUID=14a25534-a130-42e0-8eb7-f962a2662326 (large files) debian:~# dd if=/dev/zero of=ext4.img ^C100158+0 records in 100158+0 records out 51280896 bytes (51 MB) copied, 0.815768 s, 62.9 MB/s debian:~# dd if=/dev/zero of=ext4.img count=20000 20000+0 records in 20000+0 records out 10240000 bytes (10 MB) copied, 0.161352 s, 63.5 MB/s debian:~# mkfs.ext4 ext4.img mke2fs 1.41.9 (22-Aug-2009) ext4.img is not a block special device. Proceed anyway? (y,n) y Filesystem label= OS type: Linux Block size=1024 (log=0) Fragment size=1024 (log=0) 2512 inodes, 10000 blocks 500 blocks (5.00%) reserved for the super user First data block=1 Maximum filesystem blocks=10485760 2 block groups 8192 blocks per group, 8192 fragments per group 1256 inodes per group Superblock backups stored on blocks: 8193 Writing inode tables: done Creating journal (1024 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 34 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. debian:~# mkdir ext4.loop debian:~# mount ext4.img ext4.loop/ -o loop mount: unknown filesystem type 'ext4' debian:~# mount ext4.img ext4.loop/ -o loop -t ext3 mount: wrong fs type, bad option, bad superblock on /dev/loop1, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so debian:~# dmesg | tail -n1 [ 5438.516293] EXT3-fs: loop1: couldn't mount because of unsupported optional features (240). debian:~# mkfs.ext4 ext4.img mke2fs 1.41.9 (22-Aug-2009) ext4.img is not a block special device. Proceed anyway? (y,n) y Filesystem label= OS type: Linux Block size=1024 (log=0) Fragment size=1024 (log=0) 2512 inodes, 10000 blocks 500 blocks (5.00%) reserved for the super user First data block=1 Maximum filesystem blocks=10485760 2 block groups 8192 blocks per group, 8192 fragments per group 1256 inodes per group Superblock backups stored on blocks: 8193 Writing inode tables: done Creating journal (1024 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 20 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. debian:~# fsck.ext4 ext4.img e2fsck 1.41.9 (22-Aug-2009) ext4.img: clean, 11/2512 files, 1439/10000 blocks debian:~# e2fsck /dev/hda2 e2fsck 1.41.9 (22-Aug-2009) e2fsck: Filesystem revision too high while trying to open /dev/hda2 The filesystem revision is apparently too high for this version of e2fsck. (Or the filesystem superblock is corrupt) The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 debian:~# fsck.ext4 /dev/hda2 e2fsck 1.41.9 (22-Aug-2009) fsck.ext4: Filesystem revision too high while trying to open /dev/hda2 The filesystem revision is apparently too high for this version of e2fsck. (Or the filesystem superblock is corrupt) The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 debian:~# fsck.ext2 /dev/hda2 e2fsck 1.41.9 (22-Aug-2009) fsck.ext2: Filesystem revision too high while trying to open /dev/hda2 The filesystem revision is apparently too high for this version of e2fsck. (Or the filesystem superblock is corrupt) The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 debian:~#