Some VHDs can get corrupted upon shutting down the VM - Here's why

[Tech-FZ]

The issue I noticed with Windows Server 2008 R2 and Windows 8.1 and found out that some VHDs can get corrupted...

Affected EmuGUI configurations

• EmuGUI 1.1.5.5413 on Windows 10 22H2 Build 19045.(was a few months ago) x64
• EmuGUI 1.2.1.5511 on Windows 10 22H2 Build 19045.3803 x64

Reproducing the issue

1. Open EmuGUI
2. Create an amd64 VM
3. Make sure the VHD file name ends with .img, with the format being qcow2.
4. Install Windows (can be anything starting from Vista/Server 2008) as usual.
5. After the installation is complete, shut down the VM.
6. Start the VM again.

Expected behaviour The VM boots.

Host specifications OS: Windows 10 Pro 22H2 amd64 CPU: Intel Core 2 Duo E8400 RAM: 12 GB DDR3 running at 1066 MHz HDD: 250 GB HDD + 500 GB HDD Graphics: AMD Saphire Radeon R7 240 EmuGUI: 1.2.1.5511 QEMU: 8.2.0

Guest specifications (Windows 8.1) OS: Windows 8.1 Pro amd64 CPU: qemu64, 1 core out of 2 RAM: 6 GB HDD: 60 GB QCOW2 (.img file ending) BIOS: Default

Guest specifications (Windows 7) OS: Windows 7 Professional amd64 CPU: qemu64, 1 core out of 2 RAM: 4 GB HDD: 40 GB QCOW2 (.qcow2 file ending) BIOS: Default

Potential workarounds

• The file ending might play a role in how the VHD is interpreted. The .qcow2 ending might get rid of that. (Same issue)
• If not, there are still other file formats to consider.
• If you don't care about your space, the RAW format which pre-assigns the maximum size can be the most successful. (It IS successful)

[Tech-FZ]

This is a QEMU issue, sorry.