Create a virtual box disk file from physical partition

[ linux vbox ] 06 May 2022

To simulate your linux system in windows while you are using the multiple boot in your laptop

if you want to access your system directly, please see the setcion 10

1. dump your linux rootfs partition

if passiable, use USB boot to dump your partition, and make sure your target storage avaliable is enough.

sudo dd if=<dev node> of=<stored filepath> status=progress
sync
sudo chown 1000:1000 <stored filepath>

2. reduce the image file size

the dump file should be very large, we use the commands to reduce the size:

e2fsck -f -y <stored filepath>
resize2fs -M <stored filepath>

3. adjust the fstab

that is the point to simulate your physical system in your windows virtual box, because the rootfs and home directory are different with your physical system.

we just adjust the mount device with rootfs to /dev/sda1, and the swap device to /swapfile, the others we just mart them to comments

we can use the command to mount image file

sudo mount -o loop <stored filepath> <mount point>

after the modification is finished, umount it by this command:

sudo umount <mount point>

4. create a virtual disk image file

next, create a disk image file let it contains grub and others setting

truncate -s <size> <disk filepath>
parted <disk filepath> --script mklabel msdos
parted <disk filepath> --script mkpart primary ext4 5M 100%
LODEV=$(sudo losetup -f)
sudo losetup $LODEV <disk filepath> -o 5M
sudo dd if=<stred filepath> of=$LODEV

then resize again, to make sure the virtual disk’s data can be modified

sudo e2fsck -f -y $LODEV
sudo resize2fs $LODEV

5. convert to vdi file

if you don’t install virtualbox before, please install virtualbox first

sudo apt update
sudo apt install virtualbox

we use the command convert the virtual disk image file to virtual box vdi file

vboxmanage convertfromraw <disk filepath> <vdi filepath>

6. set boot information for the vdi file

the following actions should be run under Windows system open virtualbox and set the into the virtual media manager (ctrl+d), and add then set it to your virtual machine storage

mount the ubuntu Live CD (iso file) and boot the virtual machine, after the boot procedure is completed, use “Try Ubuntu”

6.1 boot repair

install the boot repair utility into the Live system

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
sudo apt-get install -y boot-repair && sudo boot-repair

then use the boot repair to create boot information.

6.2 /etc/fstab

don’t forget adjust the fstab such as mount /dev/sda1 to root folder, and use swapfile to replace the original one, mark the /home directory information to comments

/dev/sda1 / ext4 errors=remount-ro 0 1
/swapfile none swap sw 0 0
# xxxxxxx /home xxxxxxxxxxxx

7. create physical disk vmdk

get the pyhsical drive information by using Windows Power shell with command:

get-physicaldisk

then the drive information should be listed as:

Number FriendlyName       SerialNumber         MediaType CanPool OperationalStatus HealthStatus Usage            Size
------ ------------       ------------         --------- ------- ----------------- ------------ -----            ----
0      TOSHIBA DT01ACA300 675K33NAS            HDD       False   OK                Healthy      Auto-Select   2.73 TB
1      CT500P2SSD8        6479_A74D_B000_0089. SSD       False   OK                Healthy      Auto-Select 465.76 GB

we assume the pyhsical drive you want to use in virtualbox is number 1, use the command in cmd.exe to create a vmdk file that will be used in virtualbox

"%ProgramFiles%\Oracle\VirtualBox\vboxmanage.exe" internalcommands createrawvmdk -filename D:\PhyHDD.vmdk -rawdisk \\.\PhysicalDrive1

the command means we create a vmdk file in drive D, the file can be used in virtualbox

before launch virtualbox, make sure launch virtualbox as administrator if you need to use the physical drive in vmdk file

8. add vmdk file in to virtualbox

add the vmdk that is created in section 7 by using virtualbox media manager, use Ctrl+D to launch media manager then click add button, choice the vmdk file. your physical disk information should be shown in the List box.
add the vmdk media into your virtual machine stoarge

9. add physical disk partition for home directory

assume the vmdk media in your vm linux device node should be /dev/sdb, the your oringial home directory is in partition 5, add it into /etc/fstab

/dev/sdb5 /home ext4 default 0 2

after these steps, your vm linux can access the partition in your physical drive.

10. use the system directly

because the vbox supports UEFI feature weakly, so we still need to do a fake system with legacy boot and boot from the system from ssd/hdd.

** it might have some version for virutal box with SATA (AHCI) access rawdisk issue, if you impact with this issue, just change your storage to IDE interface. **

for convinent, I call the linux system in vbox is vbox-linux, and the linux for dual system is pc-linux

10.1 prepare

install a minimum setup with the same version Ubuntu or others linux <– this one is vbox-linux
make sure all of devices are recorded in pc-linux’s fstab (/etc/fstab) are using UUID
create the physical disk vmdk, the procedure is the same as setion 7
add the vmdk into the virtual machine storage, and make sure the vmdk is bottom of the storage for vbox-linux

10.2 setup the grub for vbox-linux

the point for this method is use the grub in vbox-linux then boot the system from pc-linux, it need to update the grub in vbox-linux

start the vbox-linux
run the command, let it find the os from all storages

sudo update-grub

if it works, it should be have a menu entry likes “Ubuntu 20.04 LTS (20.04) (on /dev/sdb2) will show on the /boot/grub/grub.cfg
modify the GRUB_DEFAULT index to the menu entry previous, then run the command again

sudo update-grub

after that, the you should boot into the pc-linux from virtual box by default

ChuYuan Chiang