Error phenomenon:
Input df command and the command is stuck
Can not us cd / command to access /(root) directory
Can not us ls / command to display /(root) directory
Analysis:
There may be some network storage disconnected
Solution:
Step One: Use mount command to check if there is any disconnected network storage here
# mount
Step Two: Use unmount command to unmount this disconnected network storage
# umount -f -l <nfs storage which is stuck>