Page 1 of 1

BLKCACHE_IOERR when trying to launch a VM with a vmdk linked to a local partition

Posted: 11. Nov 2018, 07:58
by Nasloon
I'd like to access (read/write) a partition on my only drive (an SSD (PhysicalDisk0)) from within a Windows 10 Guest OS.
The goal is to be able to read and write from the partition from both the Host OS and the Guest OS without having to shutdown the image.
The host is Windows 10 Pro and I've tried the normal spiel:

(All commands are run from an elevated CMD prompt and VirtualBox is Run As Administrator)

Code: Select all

C:\Program Files\Oracle\VirtualBox>VBoxManage.exe internalcommands listpartitions -rawdisk \\.\PhysicalDrive0
Number  Type   StartCHS       EndCHS      Size (MiB)  Start (Sect)
1       0x00  0   /0  /0   0   /0  /0            499         2048
2       0x00  0   /0  /0   0   /0  /0            100      1024000
3       0x00  0   /0  /0   0   /0  /0             16      1228800
4       0x00  0   /0  /0   0   /0  /0         193600      1261568
5       0x00  0   /0  /0   0   /0  /0          51200    397754368
6       0x00  0   /0  /0   0   /0  /0         188385    614402048

C:\Program Files\Oracle\VirtualBox>
The partition I'd like to access is #5 (I created this partition as an NTFS volume as Z:\).

I made sure Everyone has Full Access and that more than one user can use the drive at a time (3, to be specific).

Code: Select all

C:\Program Files\Oracle\VirtualBox>VBoxManage internalcommands createrawvmdk -filename "C:\Users\USER\Downloads\Images\Le_Z.vmdk" -rawdisk \\.\PhysicalDrive0 -partitions 5
RAW host disk access VMDK file C:\Users\USER\Downloads\Images\Le_Z.vmdk created successfully.
Once done, I launch VirtualBox and enter the settings of the desired image.

Under Storage > Storage Devices , I add Le_Z.vmdk as a hard disk.

I launch the VM, and I get this in the GUI error message:

Code: Select all

The I/O cache encountered an error while updating data in medium "ahci-0-2" (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.

Error ID: BLKCACHE_IOERR
Severity: Non-Fatal Error
I did some searching and found this: viewtopic.php?f=6&t=38914#p175089
[I can't post urls since this is my first post, so prefix it with this page's Uniform Resource Locator base.]

Here's the kicker: I only have one drive (for everything) so I can't take the drive offline to use it in VirtualBox.

I'm pretty new to VirtualBox, so I feel like I'm probably missing something simple, but I'm genuinely at a loss for what the next step might be.

Re: BLKCACHE_IOERR when trying to launch a VM with a vmdk linked to a local partition

Posted: 12. Nov 2018, 09:59
by socratis
Nasloon wrote:I did some searching and found this: viewtopic.php?f=6&t=38914#p175089
Excellent! 8)
Nasloon wrote:Here's the kicker: I only have one drive (for everything) so I can't take the drive offline to use it in VirtualBox.
Oops... Can't do it.

How about using a Shared Folder? Makes things a lot easier. Or an SMB share if you're looking for more advanced operations.