For a Linux ECS, the drive letter may change after an EVS disk is detached and then attached again, or after an EVS disk is detached and then the ECS is restarted. This is a normal phenomenon due to the drive letter allocation mechanism of the Linux system.
For example, an ECS has three disks attached: /dev/vda1, /dev/vdb1, and /dev/vdc1. The mounting parameters in /etc/fstab are as follows:
cat /etc/fstab
UUID=b9a07b7b-9322-4e05-ab9b-14b8050bdc8a / ext4 defaults 0 1 /dev/vdb1 /data1 ext4 defaults 0 0 /dev/vdc1 /data2 ext4 defaults 0 0
If /dev/vdb1 is detached, /dev/vdc1 becomes /dev/vdb1 and is mounted to /data1 after the ECS is restarted. In such a case, no disk is mounted to /data2.
To prevent this issue, use a UUID, a unique character string provided by the Linux system for disk partitions, to replace the /dev/vdx device.
In this example, run the following command to obtain the UUID of the /dev/vdb1 partition:
blkid /dev/vdb1
Information similar to the following is displayed:
[root@ecs-test-0001 ~]# blkid /dev/vdb1 /dev/vdb1: UUID="b9a07b7b-9322-4e05-ab9b-14b8050cd8cc" TYPE="ext4"
The UUID of the /dev/vdb1 partition is displayed.
vi /etc/fstab
UUID=b9a07b7b-9322-4e05-ab9b-14b8050cd8cc /mnt/sdc ext4 defaults 0 0
Repeat the preceding operations to add the UUID of the /dev/vdc1 partition and run the following command to check the disk mounting parameters:
cat /etc/fstab
The following information is displayed:
UUID=b9a07b7b-9322-4e05-ab9b-14b8050bdc8a / ext4 defaults 0 1 UUID=b9a07b7b-9322-4e05-ab9b-14b8050cd8cc /data1 ext4 defaults 0 0 UUID=b9a07b7b-9322-4e05-ab9b-14b8050ab6bb /data2 ext4 defaults 0 0