add new hard disk and ext4 file system in linux on oracle virtual box

1. create hdd from virtual media manager option

2. oepn settings of virtaul machine and add new hdd in sata controller

3. partition the /dev/sdb from fdisk:
    fdisk /dev/sdb1
4. create file system

 mkfs.ext4 /dev/sdb1

5. mount the new file system into newly created mount directory

  mkdir /u02
 mount /dev/sdb1 /u02

6. add entry for new mount point in /etc/fstab

/dev/sdb1 /u02 ext4 defaults 0 0