The df command returns duplicate or non-existent mount paths on an ECS instance that runs CentOS 6 -

This topic describes how to resolve an issue where the df -h command displays duplicate or invalid mount paths on an Elastic Compute Service (ECS) instance that runs CentOS 6.

Problem description

On an ECS instance that runs CentOS 6, the df -h command returns many duplicate or non-existent mount paths, as shown in the following figure.

Cause

The /etc/mtab file is not symbolically linked to /proc/self/mounts. This causes the df command to return abnormal output.

Normally, the /etc/mtab file is a symbolic link to /proc/self/mounts. When this issue occurs, /etc/mtab is a regular file and the symbolic link is missing. You can run the ll /etc/mtab command to check whether the symbolic link is missing.

Solution

View the information in the /proc/self/mounts file and confirm that the mount information for all file system partitions is recorded correctly.
```
cat /proc/self/mounts
```

Back up the /etc/mtab file and then replace it with a symbolic link to /proc/self/mounts.

# Back up the mtab file
mv /etc/mtab /etc/mtab.bak
# Create a symbolic link to /proc/self/mounts
ln -s /proc/self/mounts /etc/mtab

Run the df -h command again to check whether the output is normal. If non-existent mount paths are still displayed, you can manually unmount the relevant paths using the umount command.