Ticket #8485 (new defect)

Opened 4 years ago

Last modified 4 years ago

Differencing disk created from multiattach base disk is marked as auto-reset

Reported by: bitcrazed Owned by:
Priority: major Component: virtual disk
Version: VirtualBox 4.0.4 Keywords: differencing disk, multiattach
Cc: rich@… Guest type: Windows
Host type: Windows


According to the  VirtualBox docs:

Technically, a "multiattach" image behaves identically to an "immutable" image except the differencing image is not reset every time the machine starts.

This doesn't appear to be the case.

I created a VM with a dynamically sized disk, installed Win7, sysprepped the VM and shut it down. I released the HDD and used VBOXMANAGE MODIFYHD ... -TYPE MULTIATTACH to mark this HDD as immutable and that children should not auto-reset.

I then created a new VM, using the base HD which created a differencing disk for its own data.

Using VBOXMANAGE SHOWHDINFO ..., I examined the new VM's differencing disk and saw that it claims auto-reset is on.

I booted the new machine, completed the OOBE (Out Of Box Experience) and modified the desktop wallpaper. I shut down the VM and then rebooted it and was sent straight back to the OOBE again.

VirtualBox is a great product, but its poor handling of differencing disks, requiring users to delve around in the command-line tools to configure even the most rudumentary differencing scenarios, is, in my opinion, VirtualBox' biggest weakness, especially when compared to Hyper-V and VMWare.

PLEASE fix this bug and consider improving VirtualBox' GUI for handling differencing disks.


VBoxDiffDiskIssue.pdf Download (213.7 KB) - added by bitcrazed 4 years ago.
VBoxManage SHOWHDINFO output

Change History

comment:1 Changed 4 years ago by bitcrazed

... FURTHER ...

After creating and booting the dependend VM, completing the OOBE, shutting down, rebooting to find that AUTORESET is on and completing OOBE AGAIN, I shut down the VM, turned off auto-reset using modifyhd and then rebooted.

I completed OOBE once again and modified the VM's desktop. Before shutting down I checked that auto-reset was off on the differencing disk. Then I shut-down the VM and re-checked the diff disk.

Imagine my surprise that auto-reset had been turned on again. WTF???? Seriously!

Why is VirtualBox ignoring MY CHOICES and violating its own documentation by forcing differencing disks into auto-reset mode when VM's are shut down?

Changed 4 years ago by bitcrazed

VBoxManage SHOWHDINFO output

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