Linux increases root partition size

The following operations run as Root

1. Add a new partition (from the original hard disk, or add a new hard disk and partition Fdisk)
Formatted as EXT4 (MKFS.EXT4/DEV/SDB1, assumed to be/DEV/SDB1)

2. Mount the new partition to a temporary directory, such as:/mnt/tmp
Mount/dev/sdb1/mnt/tmp

3.du-sh/
Look at the size of each directory in a root directory and choose a directory of the right size
such as:/usr directory
Cp-r/usr/*/mnt/tmp

4. Modify/etc/fstab
/DEV/SDB1/USR ext3 defaults 0 0
5. Restart, if the system is operating normally, the new line in the/etc/fstab comment out, then after restarting/usr to change back to the original location, delete the rm-rf/usr/*; if not, find the reason

6. Modify the/etc/fstab, remove the comments, restart the

Linux increases root partition size