Displaying ext2, ext3 and ext4 filesystem information
The "dumpe2fs" command is used to display information about ext2, ext3 and ext4 filesystems. dumpe2fs displays superblock and block group information for filesystems present on a device.
Syntax: dumpe2fs [ -bfhixV ] [ -o superblock=superblock ] [ -o blocksize=blocksize ] device
Options -b print the blocks which are reserved as bad in the filesystem. -o superblock=superblock use the block superblock when examining the filesystem. This option is not usually needed except by a filesystem wizard who is examining the remains of a very badly cor- rupted filesystem. -o blocksize=blocksize use blocks of blocksize bytes when examining the filesystem. This option is not usu- ally needed except by a filesystem wizard who is examining the remains of a very badly corrupted filesystem. -f force dumpe2fs to display a filesystem even though it may have some filesystem feature flags which dumpe2fs may not understand (and which can cause some of dumpe2fs's display to be suspect). -h only display the superblock information and not any of the block group descriptor detail information. -i display the filesystem data from an image file created by e2image, using device as the pathname to the image file. -x print the detailed group information block numbers in hexadecimal format -V print the version number of dumpe2fs and exit.
dumpe2fs - Example Display Superblock information
john@john-desktop:~$ sudo dumpe2fs -h /dev/sda1 dumpe2fs 1.42 (29-Nov-2011) Filesystem volume name: <none> Last mounted on: / Filesystem UUID: 4daba06c-1d4d-4bbc-8f66-0a48cb20d0b4 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: (none) Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 9609216 Block count: 38419456 Reserved block count: 1920972 Free blocks: 11195030 Free inodes: 8480522 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 1014 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 8192 Inode blocks per group: 512 Flex block group size: 16 Filesystem created: Sat Oct 22 19:36:56 2011 Last mount time: Tue Jul 23 19:57:51 2013 Last write time: Wed Jul 17 12:06:55 2013 Mount count: 6 Maximum mount count: 35 Last checked: Wed Jul 17 12:06:55 2013 Check interval: 15552000 (6 months) Next check after: Mon Jan 13 11:06:55 2014 Lifetime writes: 605 GB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 First orphan inode: 6553671 Default directory hash: half_md4 Directory Hash Seed: 0206aa9d-9545-4e90-886e-d76a5511ebc7 Journal backup: inode blocks Journal features: journal_incompat_revoke Journal size: 128M Journal length: 32768 Journal sequence: 0x00242dd8 Journal start: 23267