Accessing raw partitions with VMDK

Categories:  linux
Labels:  OS, virtualization

I’m trying to access my XP partition with VirtualBox 1.4. The XP partition is on /dev/sda2 and I’d like to access /dev/sda6 as well (documents). I’ve looked in the manual and it seems that the command I need to issue to create the appropriate VMDK file is:

$ VBoxManage internalcommands createrawvmdk -filename /home/user/.VirtualBox/WinXP.vmdk -rawdisk /dev/sda -partitions 2,6 -relative -register

When I do this I get:

Error opening the raw disk: VERR_ACCESS_DENIED

If I add “sudo” in front of the command then it works and the VMDK file is created in /home/user/.VirtualBox/ However when I launch VirtualBox I get a message that tells me this virtual disk is not currently accessible. If I look in virtual disk manager I can see WinXP.vmdk but it has a yellow tag on it.

/dev/sda2 is the partition where XP is installed

/dev/sda6 contains /home (it is also where the vmdk file is stored and this is the partition that I’d like to make accessible to both host and guest)

I also try to remove the /dev/sda6 from the command:

$ sudo VBoxManage internalcommands createrawvmdk -filename /home/user/.VirtualBox/WinXP.vmdk -rawdisk /dev/sda -partitions 2 -relative -register

but I still get the same results…
Is this because I created the VMDK as root (sudo)??
Any idea?


Postby achimha » 7. Jun 2007, 08:40
You have to change the permissions on /dev/sda2 and /dev/sda6 so that the VirtualBox user can read and write to it.

When creating the VMDK as root, make sure to change owner/permissions so that VirtualBox can access it. Note that creating the VMDK also needs read access to /dev/sda (for the boot sector) so doing this as root is the best solution.

Postby zyzgak » 7. Jun 2007, 12:53
I have similar problem. I’m trying to access my linux partition under XP:

D:\xxx\pc\VirtualBox>VBoxManage internalcommands listpartitions -rawdisk \\.\Phys
 VirtualBox Command Line Management Interface Version 1.4.0
 (C) 2005-2007 innotek GmbH
 All rights reserved.

 Number Type StartCHS EndCHS Size (MiB) Start (Sect)
 1 0x83 0 /1 /1 1023/254/63 16386 63
 5 0x07 1023/1 /1 1023/254/63 131006 33559848
 6 0x07 1023/1 /1 1023/254/63 131077 301861413

 D:\xxx\pc\VirtualBox>VBoxManage internalcommands createrawvmdk -filename d:\test1
 .vmdk -rawdisk \\.\PhysicalDrive1 -partitions 1
 VirtualBox Command Line Management Interface Version 1.4.0
 (C) 2005-2007 innotek GmbH
 All rights reserved.

 ERROR: VMDK: could not create new partition data file 'd:\test1-pt.vmdk'
 Error code VERR_SHARING_VIOLATION at E:\vbox\w32-rel\src\VBox\Devices\Storage\Vmd
 kHDDCore.cpp(2228) in function vmdkCreateImage
 Error while creating the raw disk VMDK: VERR_SHARING_VIOLATION

Could somebody point my error? Or, if i have get privileges to access to that partition, how can i achieve this under XP?

Postby kilou » 7. Jun 2007, 13:16
Achimha, how do you change the permissions on /dev/sda2 and /dev/sda6?

My fstab file looks like:

/dev/sda6 /home ext3 defaults 0 2

/dev/sda2 /windows ntfs defaults,nls=utf8,umask=007,gid=46 0 1

Postby achimha » 7. Jun 2007, 13:23
You should not mount those partitions on your host. There must not by any concurrent access.

Use chmod on /dev/sda2 and /dev/sda6 to adjust the permissions.

Postby kilou » 7. Jun 2007, 13:35
chmod seems to be for files and folders only, not for entire partition. And since /dev/sda2 (where windows is installed) is a Ntfs partition, I guess linux can’t change the permission since Ntfs is read-only on linux (except if a specific driver is installed).

All I could find to change the permission is to modify fstab entry for /dev/sda2 and add “uid=1000”……but this means that the xp partition would need to be mounted in linux (this would be required to run chmod as well) :?

I’m a bit confused on how to do that.

Postby moonlight » 7. Jun 2007, 14:44
There is difference between permissions for file system of partition and permissions for partitions itself. Chmod may also work with whole sda

Postby kilou » 7. Jun 2007, 15:14
Can you post an example of the chmod command to issue to set full access permission to /dev/sda2? Does this work also if /dev/sda2 is NTFS?

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