id = 739
title = "qemu option -snapshot not work for blockdev disk"
state = "opened"
created_at = "2021-11-20T07:56:43.350Z"
closed_at = "n/a"
labels = ["Storage"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/739"
host-os = "Debian 11.1 Bullseye"
host-arch = "amd64"
qemu-version = "QEMU emulator version 5.2.0 (Debian 1:5.2+dfsg-11+deb11u1)"
guest-os = "Windows 10 21H2"
guest-arch = "amd64"
description = """If disk image configured with a -blockdev option, option -snapshot not work: all changes write to disk image instead of temporary files."""
reproduce = """1. Run qemu guest with -blockdev disk image file and -snapshot options
2. Create file test.txt on guest disk
3. Power off guest
4. Run qemu guest again
5. File test.txt present on guest disk"""
additional = """When i replace -blockdev options to legacy -drive option
```
-snapshot
-drive if=none,id=ssd1-format,media=disk,cache=none,aio=native,discard=unmap,detect-zeroes=unmap,format=qcow2,file=images/windows21h2.qcow2
-device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,device_id=drive-scsi0-0-0-0,drive=ssd1-format,id=scsi0-0-0-0,write-cache=on,bootindex=1
```
-snapshot option work fine"""