Mount a Labeled Drive Like Backup

Luke Hebert

January 24, 2022 - 2 minutes read - 401 words

Mounting a drive by its filesystem label instead of a device path like /dev/sdb1 keeps your /etc/fstab entries stable even when the kernel reassigns device names after a reboot or a hardware swap. This approach is especially handy for backup drives that you plug into different ports or controllers.

Setting a Label on Your Filesystem

Before you can reference a label, the filesystem needs one. For an ext3 or ext4 partition, use e2label:

sudo e2label /dev/sdb1 backup1

For an XFS partition, use xfs_admin:

sudo xfs_admin -L backup1 /dev/sdb1

Verify the label with blkid:

sudo blkid /dev/sdb1

You should see output that includes LABEL="backup1".

Adding the fstab Entry

Create or edit /etc/fstab and add a line that references the label:

LABEL=backup1  /backup  ext3  defaults  1 2

Field	Value	Meaning
1	`LABEL=backup1`	Filesystem label to mount
2	`/backup`	Mount point on the local system
3	`ext3`	Filesystem type
4	`defaults`	Standard mount options
5	`1`	Dump frequency (1 = yes)
6	`2`	`fsck` pass number

Make sure the mount point directory exists before rebooting:

sudo mkdir -p /backup

Testing the Entry

Always validate your fstab changes before a reboot to avoid a broken boot:

sudo mount -a

If that command returns without errors, your entry is good. You can then confirm the mount with:

df -h /backup

Why Labels Beat Device Paths

Stable across reboots. /dev/sdb1 can become /dev/sdc1 if you add or remove a disk.
Portable across ports. A USB drive plugged into a different controller gets a new device name but keeps its label.
Readable. LABEL=backup1 tells the next admin exactly what the partition is for.

Note

The label must be unique on the system. If two filesystems share the same label, mount -a will fail with an ambiguous reference error.

Quick Troubleshooting

mount: unknown filesystem type – Double-check the filesystem type in field 3 against what blkid reports.
mount: /backup: bad superblock – The label exists but the filesystem is corrupted. Run fsck on the underlying device.
Label not found – Confirm the label with sudo blkid and make sure there are no trailing spaces in your fstab line.

Using LABEL= in /etc/fstab is a small change that saves you from the classic “my backup drive is now /dev/sdc1” headache. Set the label once, write the entry, and your mount point stays put no matter what the kernel decides to call the device.

SysAdmin