Compact dynamically expanding VirtualBox CentOS image

Compact dynamic VM image

1. Delete unnecessary files from image

2. sudo yum install zerofree

3. reboot, edit kernel parameters, add 'rescue single ro'

4. remount root read-only:

    sudo mount -r -o remount /dev/mapper/vg_centos6generic-lv_root

5. null the free space (-v = verbose, -n = dry run):

    sudo zerofree -v /dev/mapper/vg_centos6generic-lv_root

6. turn off VM

7 from host OS:

    vboxmanage modifyhd --compact MachineDisk.vdi



Was able to shrink 50GB image to 36GB with only 366MB free space on the host machine.

👍