VirtualBox VMDK Physical Drive Incorrect Partition Size

Question

So I've setup VirtualBox to work just fine.

I am running Kali Linux within my VM and it can live boot properly. I created a VMDK file that pointed towards the physical drive (a USB) that I wanted to be the main drive for the VM.

What I was trying to do was to get a full install of Linux on the drive by using it as the physical drive for the VM, then do a Graphical Install onto it rather than just using UUI so that I had a Kali live boot USB.

Within the Graphical Install, I get all the way towards the end for partitioning the drive and it's showing my physical drive as 136.5 GB instead of it's actual 128 GB. I'm not understanding how it's showing that I have more space than I actually do (I've checked the partitions and it's a single partition so there's no extra space anywhere.)

I'd rather do a full install on the drive rather than a persistent live because 1) I couldn't get the persistence to work even after setting everything up correctly, and 2) because I'd rather have it save installed files and act like an entire OS than just persistent data.

My guess is that it's an issue with the VMDK or how VirtualBox is actually seeing my physical drive (USB).

At the end of the Graphical Install, I get the following error: BLKCACHE_IOERROR with the details saying this:

The I/O cache encountered an error while updating data in medium "ahci-0-0" (rc=VERR_ACCESS_DENIED). Make sure there is enough free space on the disk and that the disk is working properly. Operation can be resumed afterwards.

This tells me that it's an issue with the how the VM sees the external USB physical drive. With the VERR_ACCESS_DENIED it makes me think that my USB doesn't have the proper read/write permissions.

So basically what I'm asking is if anyone has had this issue and knows a fix for it. Or possibly if someone may know of another way for me to get a full Kali install on an external USB drive without using a VirtualBox VM (I figured this was the easiest way.)

For the record: Windows 10 Host (64-bit) Kali Linux Guest (issue with both 64 and 32)

If there's anymore information you may need, please let me know.

EDIT: I forgot to mention, that I also tried doing this off an Ubuntu Xenial host (a seperate USB live boot) and got the same issue where the drive showed up as 136.5 GB in the Graphical Install within VirtualBox.

Answer 1

The reason its most likely reporting different size, is that Linux generally uses the EXT filesystem and I am going to assume your USB Drive is formatted as NTFS. Also could be you don't have write-caching enabled or maybe some other thing.

First things first, in your host go to where you can see all your drives, right click your USB one, then click properties. Go to hardware tab, select the USB drive, the click properties in the bottom right corner. On the next window, select change settings, and change the setting to better performance instead of quick removal. This will enable write caching which is something it needs as your error pertains to I/O cache of the drive. Due note, that enabling this setting means you can't just unplug your USB Drive from the host, you will have to right click the icon in the task tray and eject it first to safely remove it without possible data loss.

Second, in your VM's setting for the guest, go to your storage, click on the controller and on the right hand side, tell it to use Host I/O cache.

Thirdly, you didn't have to do a vmdk, virtualbox has the ability to mount usb drives from the host, into the guest. You need to have the extensions installed and you can even additionally setup a usb filter to explicitly add the usb device to your guest or have it detect it anyhow and make sure in the USB filters area in the settings of the VM guest, that you select the appropriate usb version that your usb drive uses and the port its connected to. If both the device and the usb port can handle USB 3.0 devices, select usb 3.0 in the usb filters area.

here is guide for the third part USB Device in Guest

the fourth thing you are going to want to do, is format the drive that Kali linux needs it to be first, then attempt to install kali linux to it. And because the device should natively be detected it should be able to install a live version of the OS instead.

Hopefully this resolves your problem you are having. Do let us know if you try this and it still does not work as it could be a bug within virtualbox or maybe something else.