Windows | 7qcow2

Let’s start from scratch. You’ll need a Windows 7 ISO (ensure you have a legal license key).

| Problem | Solution | |---------|----------| | BSOD 0x0000007B on boot | Missing VirtIO driver. Reinstall with viostor driver loaded. | | qcow2 grows too large | Enable discard='unmap' and run sdelete -z inside guest monthly. | | Very slow disk performance | Switch from IDE/SATA to VirtIO block + cache='writeback'. | | Windows 7 cannot boot after snapshot revert | Corrupt boot config. Boot from Windows 7 ISO → Repair → Bootrec /fixboot. | windows 7qcow2

Windows 7 wasn't designed for modern virtualization. Add these options to your VM XML (or Virt-Manager advanced settings): Let’s start from scratch

| Setting | Value | Why | |---------|-------|-----| | Cache mode | writeback or none | Improves I/O (avoid writethrough) | | AIO | native | Lower latency | | Discard | unmap | Reclaims space from deleted files | | Driver | virtio-blk or virtio-scsi | Faster than IDE/SATA | disk type='file' device='disk'&gt

Example libvirt disk block:

<disk type='file' device='disk'>
  <driver name='qemu' type='qcow2' cache='writeback' io='native' discard='unmap'/>
  <source file='/var/lib/libvirt/images/win7.qcow2'/>
  <target dev='vda' bus='virtio'/>
</disk>