[Solved] BLKCACHE_IOERR when using real disk as vmdk

[mberemand]

When I attempt to use a virtual machine where one of the mounted disks is a vmdk pointing to a real disk, VirtualBox throws the error:

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.

Error ID: BLKCACHE_IOERR
Severity: Non-Fatal Error

HRID-2018-02-19-11-30-55.zip

Log file

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The disk in question is not locked for read/write by the host operating system in any way. The createrawvmdk command was run as Administrator and the virtual machine was also started as Administrator. If I turn on "Use Host I/O Cache" the error does not appear but the guest OS hangs. It is as if the disk is being used in read-only mode, even though Diskpart says it isn't.

Host machine is running Windows 10 64-bit. Various Windows and Linux guests are all affected. VirtualBox version 5.2.6 and 5.1.32 both encountered this error.
EDIT: version 5.2.7 build 120865 also doesn't work.

[mberemand]

bump

[mpack]

This subject has been dealt with several times in the past (since Vista in fact), I'd have thought that a search would turn something up.

e.g. viewtopic.php?f=6&t=38914

[mberemand]

I used several search terms in this forum as well as other sites and I only ever found suggestions to make sure I was running VBox as admin and to enable Host I/O caching. I did not see that particular thread. Previously, I made sure the READONLY attribute was cleared for the disk I was using, but that thread also mentions that I should OFFLINE the disk. After doing so, the problem is resolved. I'm not sure why it mattered, as I've been using the same configuration on Windows 7 and 10 hosts for a while and only just now encountered this issue with my most recent Windows 10 computer. I've never had to OFFLINE disks for them to work for raw vmdk. I could even get away with leaving drive letters assigned if the filesystem was ext4 or something that the Windows host couldn't read.

Anyways, thank you for your help.

[Asad MIrza]

Issue resolved ,
Go to
->Virtual Box settings
->Storage
->Controller:SATA
(Check the option "Use Host I/O Cache")