UUID (Universally Unique Identifier) is used to identify storage devices on a system. When you add the file system we will add uuid or label.

We can easily generate the UUID in a system using uuidgen command

# uuidgen


How to change the UUID for Logical Volume:

Find out current lvm uuid:

To determine the UUID for the device /dev/mapper/vg01-linux01, can get using blkid command,

# blkid /dev/mapper/vg01-linux01
/dev/mapper/vg01-linux01: UUID="4ed7925b-b35a-43ca-abd1-e9db6fb80364" TYPE="ext4"

The output is device name, label name, UUID and file system type ext4

Generate New UUID.

# uuidgen

Using tune2fs command can be changed the UUID for that specific device name.

# tune2fs /dev/mapper/vg01-linux01 -U 45ce9e8c-4993-4247-b08b-e8092b898b7e

tune2fs 1.42.8 (20-Jun-2013)

After changes you can check it .

# blkid /dev/mapper/vg01-linux01

/dev/mapper/vg01-linux01: UUID="45ce9e8c-4993-4247-b08b-e8092b898b7e" TYPE="ext4"

How to change the UUID for Partition:

For example, do you want to change the device  /dev/sda1 follow the steps,


# tune2fs /dev/sda1 -U 08ad6121-a3a7-4207-9778-ae17f1d55dc4
tune2fs 1.42.8 (20-Jun-2013)

# blkid /dev/sda1
/dev/sda1: UUID="08ad6121-a3a7-4207-9778-ae17f1d55dc4" TYPE="ext4"

Once you have changed that should be update in file system /etc/fstab

UUID Help:

# uuidgen --help

 uuidgen [options]

 -r, --random     generate random-based uuid
 -t, --time       generate time-based uuid
 -V, --version    output version information and exit
 -h, --help       display this help and exit

To find out uuidgen version,

# uuidgen -V
uuidgen from util-linux 2.20.1

How to generate UUID using PHP code,

echo exec('uuidgen');