• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer navigation

The Geek Diary

  • OS
    • Linux
    • CentOS/RHEL
    • Solaris
    • Oracle Linux
    • VCS
  • Interview Questions
  • Database
    • oracle
    • oracle 12c
    • ASM
    • mysql
    • MariaDB
  • DevOps
    • Docker
    • Shell Scripting
  • Big Data
    • Hadoop
    • Cloudera
    • Hortonworks HDP

CentOS / RHEL : How to change the UUID of the filesystem

by admin

The device node name of a disk (/dev/sda, /dev/hda, /dev/vda, etc.) may change in some situations. For example, after switching cables around or upgrading certain packages, sda & sdc could swap places. This causes problems when /etc/fstab references filesystems by the disk names. It is not safe to use block device node names like /dev/sda1 and /dev/vdb2 to refer to filesystems in /etc/fstab.

Instead, use filesystem UUIDs (universally unique identifiers) or labels. Either of these allows for identifying a filesystem without resorting to ephemeral block device names.

Note : UUIDs and labels are not required if a filesystem resides on an LVM logical volume, as in default RHEL/CentOS installations.

Check the current UUID of the filesystem

1. To find of the current UUID of the filesystem you can use either of the below commands.

# blkid /dev/sdc1
/dev/sdc1: UUID="94ddf54e-53f7-4a1a-bd2f-d0a01ee448d1" TYPE="ext4"
# dumpe2fs /dev/sdc1 | grep UUID
dumpe2fs 1.42.9 (28-Dec-2013)
Filesystem UUID:          94ddf54e-53f7-4a1a-bd2f-d0a01ee448d1

You can also view the UUID in the file /etc/fstab, if there is an entry done manually for the filesyste.

# grep data /etc/fstab
UUID="94ddf54e-53f7-4a1a-bd2f-d0a01ee448d1"       /data     ext4    defaults        0 2

1. Changing UUID using tune2fs

1. To be able to change the UUID of the filesystem, it must be umounted first.

# umount /data

2. The tune2fs command allows the UUID to be changed using the -U flag. The -U flag allows generation of a random UUID or time-based UUID.

# tune2fs -U random /dev/sdc1
tune2fs 1.42.9 (28-Dec-2013)

3. When modifying existing UUIDs, make sure to update any references to the old labels in fstab. First check for the new UUID and then make appropriate changes in the /etc/fstab file.

# blkid | grep sdc1
/dev/sdc1: UUID="d2c27808-f88f-44bc-bb1d-de3b03d133e4" TYPE="ext4"
# vi /etc/fstab
UUID="d2c27808-f88f-44bc-bb1d-de3b03d133e4"       /data     ext4    defaults        0 2

4. Mount the filesystem back again.

# mount /data
How to Change the filesystem Labels in CentOS/RHEL

Filed Under: CentOS/RHEL 6, CentOS/RHEL 7, Linux

Some more articles you might also be interested in …

  1. How To Execute The Pstack Command On CentOS/RHEL
  2. arecord Command Examples in Linux
  3. “No space left on device” – kdump generation issue (CentOS/RHEL)
  4. pmount: command not found
  5. ufw Command Options
  6. dmesg: command not found
  7. Linux OS Service ‘anacron’
  8. What is the purpose of .bash_profile file under User Home Directory In Linux
  9. What is the difference between insmod and modprobe
  10. aptitude Command Examples in Linux

You May Also Like

Primary Sidebar

Recent Posts

  • pw-cat Command Examples in Linux
  • pvs: command not found
  • pulseaudio: command not found
  • pulseaudio Command Examples in Linux

© 2023 · The Geek Diary

  • Archives
  • Contact Us
  • Copyright