virtualbox.org

I made a vmdk file so that I can boot Ubuntu from my USB Drive using this command: This worked, I am able to boot up but all of the sudden it crashes and I get this error message:
The I/O cache encountered an error while updating data in medium ahci-0-0 (rc=VERR_ACCES_DENIED). Make sure there is enough free space on the disk and that the disk is working properly. Operation can be resumed afterwards.
With the ID: BLKCACHE_IOERR
I tried to use diskpart and tried to do this command on the USB Drive: This didn't make much of a difference.
I did try it while running virtualbox as an administrator.
Does anyone have any idea what I should do?

Win7 host? If so then read the following :-
Enabling raw access to Win7 / Win2k8 disks.

Please be aware that most volunteers here will be reluctant to help anyone use the raw disk feature. It is flagged in the user manual as a dangerous, expert level function whose misuse can result in disk corruption which is not necessarily restricted to the intended disk. My personal definition of "expert level" is someone who doesn't need my advice.

Yes win7 host. I already tried what you've linked to as I said and it didn't do too much. UAC is off too. Thanks though!

I know, I won't do anything too risky and I will be very careful. Thanks for the warning.

Having same issue.

Using Ubuntu 15.04, installed on flash drive.

Using lates VB (4.3.28 r100309)
Tryed everything in list above, including disabling UAC, removing all attributes from all files/folders on drive, even hidding drive in explorer(be removing assigned button in diskmgmt).
Even tryed different connections type of flesh in windows(enable/disable hot turn-of for caching)

No sussess.
Ubuntu start loading fine. it even loads some GUI. But in the middle of loading I cought this exception. Will try another linux, but I bealive something wrong with access rigths/caching.

Any Ideas?
________________________
got it worked with this tool: http://reboot.pro/topic/15069-lockvolume/ (from here: viewtopic.php?f=6&t=49850#p227596)

as always, got an answer myself right after writting to forum