[VBox 4.3.26] MS-DOS fails to format hdd (bad track 0), works in previous version -> not a bug

[agaace]

I've tried recreating old virtual machines (created with a previous Virtual Box version) with the latest version: 4.3.26. Unsuccessfully.

Specifically, I tried MS-DOS 2.0, 2.1, 3.1 and 3.30. While the OS starts ok from a virtual floppy disk image, it fails to format the virtual HDD. I tried with a new expandable 16MB VHD and VDI files, both fail with message "Disk unusable, bad track 0".

I reverted back to Virtual Box version 4.3.12, repeated the exact same steps. I was able to successfully format the virtual hard drive (created a new VHD file).

REPRO STEPS: With VirtualBox 4.2.26: 1) Create a new machine with 16MB hdd (expandable, VHD) and 8 MB ram, name it "IBM DOS 2.00". 2) Insert the attached floppy image and boot the machine (note: the image is copyrighted, I am the owner of the original software I purchased, attaching it only for debugging purposes, please delete after the bug is fixed) 3) Press enter twice to accept current date and time. 4) Enter command "fdisk", press enter to create a partition, enter again to use the entire hdd. Wait foe the OS to reboot. 5) Enter command "format C: \S \V".

EXPECTED: 6) C: drive is successfully formatted as a MS-DOS bootable drive.

ACTUAL: 6) "Disk unusable - bad track 0" error. If you repeat steps 1-5 in VirtualBox version 4.3.12, the result is as expected.

[agaace]

MS-DOS 2.00 VHD

[agaace]

EDIT:

Host is Windows 8.1, guest is MS-DOS 2.00.

The command is "format C: /S /V", not "format C: \S \V".

[agaace]

Actually I think I figured out the issue and it is not a bug in VirtualBox.

IBM/MS-DOS 2.00 will *see* (and partition) hdd above 16 MB but will fail to format/use it correctly, while it will have no issues with hdd up to 16 MB.

Same with IBM/MS-DOS 3.10 - it will *see* (and partition) hdd above 32 MB, but will also fail to format/use it correctly, while it will have no issues with hdd up to 32 MB. When I was repro-ing the issue on different virtual box version, I messed up the OS/hdd combination, because I was not aware of the limitations.

I think this ticket can be now closed.

[Michael Thayer]

Thanks for the investigation and the feedback.