fsck

LPIC-1LINUX

Warning: Repairing tools for your file system must be used with caution! While it is safe to only check your file system for inconsistencies, actually attempting a repair may worse the situation. When using these tools, the system must be always unmounted. When you need to check the "/" (root partition), you need to do this from live media.

tl;dr

For repairing tools to work they need your FS to be always unmounted.

e2fsck, fsck.ext2/3/4 with -n it only checks

xfs_repair with -n it only checks

xfs_db “debugger”, it only checks (it inspects the metadata)

btrfs check it only checks

Changing the label:

tune2fs -L "New label" /dev/sdXX (ext2/3/4)

xfs_admin -L "New label" /dev/sdXX

btrfs filesystem label <mount_point or device> "New label"

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1 Repairing the system

Use these commands when a file system is corrupted or won't mount.

File System Command Notes

ext2/3/4 e2fsck Usually called via the fsck wrapper. Must be unmounted. -n flag to check only.

xfs xfs_repair Must be unmounted. -n flag to check only.

xfs_db db stands for "Debugger". To view or debug internal metadata. Must be unmounted.

Btrfs btrfs check Must be unmounted.

All the following commands are soft links to e2fsck command:

ls /sbin/fsck.ext?
/sbin/fsck.ext2 /sbin/fsck.ext3 /sbin/fsck.ext4

2 Changing the label of a FS

Warning on changing the label: If you are changing the label for the Root (/) and Boot (/boot) partitions, if your /etc/fstab file is configured to mount your drive using the old label (e.g., LABEL=CentOS7), your machine will fail to boot next time because that label no longer exists! Check your /etc/fstab before making any changes.

a) ext2/3/4

# tune2fs -L "New label" /dev/sdXX

Verify the change:

# tune2fs -l /dev/sdXX | grep <label_name>

b) XFS (the system needs to be unmounted to apply the changes, use a Live ISO for the root and boot FS)

# xfs_admin -L "New label" /dev/sdXX or /dev/mapper/[Volume_name]

Verify the change:

# xfs_admin -l /dev/sdXX

c) btrfs

# btrfs filesystem label <mountpoint_or_device> "New label"

Verify the change:

# btrfs filesystem label <mount_point or device>

4 Review

Question: You are trying to mount an XFS partition, but the kernel reports "structure needs cleaning." You want to check for errors without making any changes. Which command do you use?

Answer: xfs_repair -n /dev/sdXX (The -n is the key for "no changes").

Question: Which command allows you to manually inspect the inodes of an XFS file system?

Answer: xfs_db

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