Ext4
ext4 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
- 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 (See also: xfs_growfs)
resize2fs
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
Activities
Basic
- Create an file ext4 system using:
mkfs.ext4 - Create an ext4 file system an mount it using systemd: https://codingbee.net/rhcsa/rhcsa-mount-filesystems-during-boot-time-using-systemd
Advanced
- 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
- Learn about Lazy initialization feature of ext4: https://www.thomas-krenn.com/en/wiki/Ext4_Filesystem#Lazy_Initialization
See also
- ZFS, LVM (lvcreate), mdadm, fdisk and partitions
- XFS default filesystem for RHEL 7.0 in 2014.
- tune2fs which allows among other actions to modify reserved space[8]
- ext2online
- JFS2, mkfs.jfs (Linux), jfsutils and xfs_growfs [9]
- chfs (AIX)
- inode, superblock and block size
statcommand.stat -c %h -- YOUR_FILE- mount and findmnt[10]
- fsck
- chmod, setuid and setgid
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