Ext4

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ext4 (2008) journaling file system or fourth extended filesystem is a journaling file system for Linux and it is the default file system for many Linux distributions such as Ubuntu and Debian. RHEL default fs is XFS.

Since Linux kernel 4.1 on June 2015[1], ext4 natively supports file encryption

Basic commands[edit]

  • mkfs and mke2fs
  • Creating an ext4 filesystem: (by default since 2010 will do a quick and lazy initialization [2])
Creating an ext4 in a disk
mkfs.ext4 /dev/sdX
Creating an ext4 FS in an LV:
mkfs.ext4 /dev/vg01/lv01
To prevent lazy initialization mkfs.ext4 -E lazy_itable_init=0,lazy_journal_init=0 /dev/mapper/fc-root[3]

resize2fs[edit]

resize2fs[4] file system resizer for ext2/ext3/ext4 (resize2fs /dev/mapper/VolGroup-lv_root). Online resize (expand) is supported in resize2fs since 2006[5].[6]. resize2fs code: https://github.com/tytso/e2fsprogs/blob/master/resize/resize2fs.c. See also: ext2online

EXT4 Features timeline[edit]

Activities[edit]

Basic

  1. Create an file ext4 system using: mkfs.ext4
  2. Create an ext4 file system an mount it using systemd: https://codingbee.net/rhcsa/rhcsa-mount-filesystems-during-boot-time-using-systemd

Advanced

  1. Configure an LVM Volume with an ext4 filesystem: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/high_availability_add-on_administration/s1-lvmsetupnfs-haaa
  2. Learn about Lazy initialization feature of ext4: https://www.thomas-krenn.com/en/wiki/Ext4_Filesystem#Lazy_Initialization
  3. Review ext4 journalctl logs

Mount options[edit]

Related terms[edit]

See also[edit]

  • https://lwn.net/Articles/639427/
  • https://en.wikipedia.org/wiki/Ext4#Features
  • https://www.thomas-krenn.com/en/wiki/Ext4_Filesystem#Lazy_Initialization
  • https://manpages.debian.org/stretch/e2fsprogs/resize2fs.8.en.html
  • https://github.com/tytso/e2fsprogs/commit/bf69235ad0073c80386b70caba0e1b58e5f85697
  • https://www.technomenace.com/2014/08/how-to-extend-lvm-on-qcow2-images/
  • https://en.wikipedia.org/wiki/Ext4#Features
  • https://linux.die.net/man/8/xfs_growfs