# Changing the Disk Identifier in the fstab File to UUID

#### Scenarios

When optimizing a Linux private image, you need to change the disk identifier to UUID in the fstab configuration file of the ECS.

#### Procedure

- Take CentOS 7.0 as an example. Run blkid to obtain the UUIDs of all partitions. Modify the /etc/fstab file and use the partition UUIDs to configure automatic partition mounting.

1. Log in to the ECS as user root.
2. Run the following command to query all types of mounted file systems and device UUIDs:

   blkid

   The following information is displayed:

       /dev/xvda2: UUID="4eb40294-4c6f-4384-bbb6-b8795bbb1130" TYPE="xfs"
       /dev/xvda1: UUID="2de37c6b-2648-43b4-a4f5-40162154e135" TYPE="swap"

3. Run the following command to query the fstab file:

   cat /etc/fstab

   The following information is displayed:

       [root@CTU1000028010 ~]# cat /etc/fstab
       /dev/xvda2  /       xfs     defaults    0 0
       /dev/xvda1  swap    swap    defaults    0 0

4. Check whether the disk identifier in the fstab file is the device name.
   - If the disk is represented by UUID, no further operation is required.
   - If the disk is represented by the device name, go to 5.
5. Run the following command to open the fstab file:

   vi /etc/fstab

6. Press i to enter editing mode and change the disk identifier in the fstab file to UUID.

- Take CentOS 7.1 as an example. Run blkid to obtain the UUIDs of all partitions. Modify the /etc/fstab file and use the partition UUIDs to configure automatic partition mounting.

1. Log in to the ECS as user root.
2. Run the following command to query all types of mounted file systems and device UUIDs:

   blkid

       /dev/xvda2: UUID="4eb40294-4c6f-4384-bbb6-b8795bbb1130" TYPE="xfs"
       /dev/xvda1: UUID="2de37c6b-2648-43b4-a4f5-40162154e135" TYPE="swap"

   Before the change:

       [root@CTU1000028010 ~]# cat /etc/fstab
       /dev/xvda2  /       xfs     defaults    0 0
       /dev/xvda1  swap    swap    defaults    0 0

   After the change:

       [root@CTU1000028010 ~]# cat /etc/fstab
       UUID=4eb40294-4c6f-4384-bbb6-b8795bbb1130  /       xfs     defaults    0 0
       UUID=2de37c6b-2648-43b4-a4f5-40162154e135  swap    swap    defaults    0 0

3. Press Esc, enter :wq, and press Enter. The system saves the configuration and exits the vi editor.
4. Run the following command to verify the change:

   cat /etc/fstab

   The change is successful if information similar to the following is displayed:

       [root@CTU1000028010 ~]# cat /etc/fstab
       UUID=4eb40294-4c6f-4384-bbb6-b8795bbb1130  /       xfs     defaults    0 0
       UUID=2de37c6b-2648-43b4-a4f5-40162154e135  swap    swap    defaults    0 0

Parent topic: Optimizing a Linux Private Image