How can I extend partition in virtual box ?

It's quite easily for extend partition in virtual box. You can follow step by step to complete your task. In example I'm using CentOS

1. Power off your CentOS virtual machine
2. Go into the directory of your *.vdi image. If you don't know where it is, look at your Virtualbox Manager GUI virtualbox -> settings -> storage -> *.vdi -> location e.g. mine is located under ~/VirtualBox VMs/CentOS7/CentOS.vdi
3. Back up your image just in case anything goes wrong
   $ cp CentOS7.vdi CentOS7.backup.vdi
4. Resize your virtual storage size, e.g. 200 GB
   $ VBoxManage modifyhd CentOS7.vdi --resize 204800
5. Power on your CentOS virtual machine, issue
   $ sudo fdisk -l

   Device Boot      Start         End      Blocks   Id  System
    /dev/sda1   *        2048     1026047      512000   83  Linux
    /dev/sda2         1026048   209715199   104344576   8e  Linux LVM

6. Use fdisk utility to delete/create partitions
   $ sudo fdisk /dev/sda
7. You are in the fdisk utility interactive mode, issue following commands: (mostly just follow the default recommendation)
   d - delete a partition
   2 - select a partition to delete (/dev/sda2 here)
   n - create a new partition
   p - make it a primary partition
   2 - make it on the same partition number as we deleted
   <return> - set the starting block (by default)
   <return> - set end ending block (by default)
   w - write the partition and leave the fdisk interactive mode
8. Reboot your CentOS machine
   $ sudo reboot
9. Resize the physical volume and verify the new size
   $ sudo pvresize /dev/sda2
   $ sudo pvscan
10. Take a look at your logical mapping volume to see what volume you want to enlarge, in my case, /dev/mapper/centos-root
11. Resize the file system by adding -r option, it will take care of resizing for you
    $lvextend -r -l +100%FREE /dev/mapper/centos-root
12. Resize the file system:
    $resize2fs /dev/mapper/fedora-root
    For CentOS 7: $xfs_growfs /dev/mapper/fedora-root
13. Last check:
    $df -h.

Note: awslagi.com