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Use Ext4 for conservative server roots, virtual-machine roots, uncomplicated data volumes, and Linux-only external backup disks. It journals metadata and has broad recovery tooling, but it does not checksum ordinary file contents or provide native snapshots [19]-[21]. Encryption is LUKS2 below Ext4.
Use current mke2fs defaults instead of hardcoding feature bits, inode ratios,
or geometry:
sudo mkfs.ext4 -L <label> /dev/mapper/<mapping>If selective fscrypt directories are required, create the filesystem with the feature explicitly enabled:
sudo mkfs.ext4 -O encrypt -L <label> /dev/mapper/<mapping>Root filesystem:
UUID=<EXT4-UUID> / ext4 defaults,errors=remount-ro 0 1
Ordinary data filesystem:
UUID=<EXT4-UUID> /srv/data ext4 defaults,errors=remount-ro 0 2
External disk on a systemd host:
UUID=<EXT4-UUID> /srv/backup ext4 defaults,errors=remount-ro,nofail,x-systemd.automount,nodev,nosuid 0 2
Use normal Unix ownership and modes inside Ext4. Add noexec to a removable
or content-only volume only when software execution is not intended.
Do not add data=ordered, barrier=1, or commit=5: ordered data mode,
barriers, and a five-second commit interval are already defaults [19]. Do not
increase the commit interval to 30, 60, or 300 seconds. Ext4 metadata checksums
protect filesystem structures, not ordinary file data [20]. Backup software
must provide versioning and content verification.