There are many devices or mount points mounted on system. But sometimes, we need to mount these mount points by unique ID. This case generally happens in network because in same network, might have same name mount points on different disks. To avoid this conflict, we will mount the mount points by their block ID which is always unique.
Before doing entry in /etc/fstab file, we need to find block ID of that file. We will do it by following commands as follows:
root@hello:~/myhome/test# blkid /dev/sda1
/dev/sda1: UUID="s91ed12-d675-46bf-a42f-07fgc2313505" TYPE="ext3"
root@hello:~/myhome/test# blkid /dev/sda3
/dev/sda3: UUID="k4161839-0b4d-45aa-b4d5-49c76g989628" TYPE="ext3"
As per above example, block id will show for only created partitions and we need to provide one parameter for this command and that is partition name.
After this, we can mount file system or partition on operating system with this block ID. It is permanent block id for this partition and it will never change. For each physical partition, there is unique block id for it.
Example of /etc/fstab file configuration by UUID.
# swap was on /dev/sda5 during installation
UUID=72c7301e-239b-44a0-9ccd-41693680d91c none swap sw 0 0
If you see in above example, we have used UUID for that device not device or partition name while mounting it in /etc/fstab file.
Chkconfig command in Linux Basic Uses of tar command