During maintenance on a CentOS 9 file server you replaced a failed backplane and re-seated all drives. After the next reboot the system drops into emergency mode and displays:
mount: /data: wrong fs type, bad option, bad superblock, missing codepage or helper program, or other error systemd: data.mount: Failed with result "exit-code".
Before the maintenance an ext4 volume on /dev/sdb1 was automatically mounted at /data. Running lsblk -f now shows: /dev/sdb1 ext4 fb3448d9-1a9d-4c30-9d1e-89cfa7320d72 /data (not mounted)
The /etc/fstab file still contains: UUID=ab12c3de-45f6-7890-1234-56789abcdeff /data ext4 defaults 0 2
Which action will MOST quickly restore a normal boot and make /data available without jeopardizing the existing data?
Comment out the /data entry in /etc/fstab and reboot, letting administrators mount the partition manually when required.
Replace the stale UUID in /etc/fstab with fb3448d9-1a9d-4c30-9d1e-89cfa7320d72 and run mount -a to verify the change.
Re-create the filesystem on /dev/sdb1 with mkfs.ext4, then restore the data from backup before rebooting.
Run fsck -f on /dev/sdb1 and then use tune2fs -U ab12c3de-45f6-7890-1234-56789abcdeff to reset the original UUID before rebooting.
The ext4 filesystem is healthy, but the identifier that systemd uses to locate it has changed. Because fstab still points to the old UUID the mount attempt fails and the boot process halts. Editing /etc/fstab so that the entry uses the current UUID reported by lsblk/blkid, then testing with mount -a, immediately re-establishes the correct mapping and requires no destructive operations. Re-formatting the partition would erase data, commenting out the line only masks the symptom, and changing the filesystem's UUID with tune2fs adds unnecessary risk and time compared with simply fixing one line in fstab.
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What is a UUID in the context of Linux filesystems?
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What would happen if the UUID in `/etc/fstab` does not match the actual UUID of a partition?