Centos 6.8 uses LVM to add multiple new hard disks and increase the root directory capacity

My system is Centos 6.8 64-bit. I have added 5 new hard disks and all the space has been increased to the root directory.
All operations are performed as root user and under ssh.

1. Check the hard disk status

 fdisk -l

2. Partition each hard disk into 1 zone and set it to lvm format

 fdisk /dev/sdb

Enter n, p, 1, Enter, Enter, t, 8e, w respectively to create the following partitions:
/dev/sdb1, /dev/sdc1, /dev/sdd1, /dev/sde1, /dev/sdf1

3. Create a physical volume (PV)
First check the existing physical volume (PV)

 pvdisplay

Create a physical volume (PV)

 pvcreate /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1

4. Add PV to volume group (VG)

 vgdisplay

Add the new PV to the vg volume group

 vgextend vg /dev/sdb1

Add all partitions to the vg volume group

5. Check the lv path name through lvdisplay because mkfs.ext4 will use this name instead of the name of the created lv.

 lvdisplay

6. Format partition

 mkfs.ext4 /dev/sdb1

7. Expand the root directory capacity

 lvextend -L +1.8T /dev/vg/root

7. Refresh the root directory capacity

 resize2fs /dev/vg/root