tune2fs

Tune2fs is a Linux command-line utility from the e2fsprogs package used to adjust tunable parameters of ext2, ext3, and ext4 filesystems. It changes values stored in the filesystem’s superblock, enabling administrators to influence behavior such as how and when the filesystem is checked, how many blocks are reserved for root, and which features are enabled. Changes can improve reliability or performance but should be applied with caution, ideally with the filesystem unmounted.

Scope and usage

Tune2fs works with ext2/3/4 filesystems and is commonly used to configure:

- Reserved blocks: tune2fs -m to set the percentage of blocks reserved for the superuser.

- Mount count and fsck interval: tune2fs -c for maximum mount count, tune2fs -i for the interval between automatic fsck checks.

- Error handling behavior: tune2fs -e to specify actions such as continue, remount-ro, or panic when an error is encountered.

- Enabled features: tune2fs -O to enable or configure filesystem features (for example, 64bit, has_journal, etc.).

- Metadata and identity: tune2fs -L to set the volume label, tune2fs -U to assign a UUID.

- Viewing current settings: tune2fs -l device prints the current tunable parameters.

cautions

Changing tunables can affect filesystem integrity and behavior. It is typically safer to unmount the filesystem before modifying parameters and to back up important data beforehand. Some changes may require remounting or a reboot to take full effect, depending on the parameter and kernel support.

Examples

- List current tunables: tune2fs -l /dev/sdXN

- Remove reserved blocks: tune2fs -m 0 /dev/sdXN

- Change fsck interval to 30 days: tune2fs -i 30d /dev/sdXN

- Set max mount count to 50: tune2fs -c 50 /dev/sdXN

- Enable a feature, e.g., 64bit: tune2fs -O 64bit /dev/sdXN

See also

e2fsprogs, mke2fs, and fsck for related filesystem management tools.