Bootcamp, use host i/o cache, and 5.0.6
Posted: 11. Oct 2015, 18:26
I've had a Windows 7 Bootcamp partition configured as a guest in VirtualBox for well over a year. Everything worked fine through version 5.0.0 of VirtualBox. When I tried versions 5.0.2, 5.0.4, and 5.0.6, I got a VERR_NOT_SUPPORTED error while opening the vmdk file that pointed to the raw disk. I opened ticket #14613 to report the bug, and another user indicated that they had the same problem.
I started digging into the problem again to determine if I could change the configuration to work around the problem. In the bug tracker, ticket #14461 indicated that raw disk access was failing when the "Use Host I/O Cache" option was disabled on the storage controller. I enabled this option on my Bootcamp guest's SATA controller with VirtualBox 5.0.6, and the guest is booting successfully again.
Is the "Use Host I/O Cache" option required for all raw disk access now? Is there any harm in enabling this option? What changed between 5.0.0 and later versions that made my Bootcamp guest fail with the VERR_NOT_SUPPORTED error until I enabled this option?
I started digging into the problem again to determine if I could change the configuration to work around the problem. In the bug tracker, ticket #14461 indicated that raw disk access was failing when the "Use Host I/O Cache" option was disabled on the storage controller. I enabled this option on my Bootcamp guest's SATA controller with VirtualBox 5.0.6, and the guest is booting successfully again.
Is the "Use Host I/O Cache" option required for all raw disk access now? Is there any harm in enabling this option? What changed between 5.0.0 and later versions that made my Bootcamp guest fail with the VERR_NOT_SUPPORTED error until I enabled this option?