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Libvirt Snapshot Question
by Elias Mobery 02 Dec '21

02 Dec '21

Hi everybody! I'm using a snapshot purely for writes and was wondering if it's possible to clear/empty the snapshot after it reaches a certain size? Created with: virsh snapshot-create-as --disk-only I tried deleting and recreating it but get an error at deletion: virsh snapshot-delete Error: source for disk 'vda' is not a regular file I also tried virsh snapshot-create-as --no-metadata --disk-only But the same error as above pops up when trying to delete. Any ideas?

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qemu-img create with extended_l2=on, followed by virt-install
by Richard Taubo 01 Dec '21

01 Dec '21

Hi! I have read the following blog post: https://blogs.igalia.com/berto/2020/12/03/subcluster-allocation-for-qcow2-i… and watched the video displayed there. 1) To make qcow2 as fast as possible, does it make sense to do the following: [#] qemu-img create -f qcow2 -o extended_l2=on,cluster_size=128k my_image.qcow2 1000GB And then: [#] virt-install —name=MyVM --disk path=my_image.qcow2,size=1000 . . . Will this overwrite the qcow2 file already created or will it keep its characteristics? Does it make sense? 2) I wont’t be moving the VM around much and have the space I need, so I wonder if it will be faster to do the following: [#] qemu-img create -o preallocation=full -f qcow2 my_image.qcow2 1000GB And then: [#] ] virt-install —name=MyVM --disk path=my_image.qcow2,size=1000,bus=scsi,sparse=false . . . (Running bus=scsi so I can trim the image ). I could use a dedicated disk for the VM instead of using qcow2, but I like the flexibility of qcow2. Thanks a lot for any information about this! :-) Best regards, Richard Taubo

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migrate libvirt config between machines
by daggs 30 Nov '21

30 Nov '21

Greetings, I'd like to migrate my current libvirt config from one machine to another, what is the best way to do so? Thanks

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qemu-img create with preallocation=full and compression_type=zlib
by Richard Taubo 30 Nov '21

30 Nov '21

Hi! When running this command on Fedora 35 I get: [#] qemu-img create -o preallocation=full -f qcow2 /var/vm_mail/mytest.qcow2 10GB => Formatting '/var/vm_mail//mytest.qcow2', fmt=qcow2 . . . preallocation=full compression_type=zlib . . . ." Question: When using 'preallocation=full’ I was surprised that the resulting qcow2 image includes the 'compression_type=zlib’ part. Why/when is this compression used when the qcow2 image is fully preallocated? Thanks for input on this! :-) Best regards Richard Taubo

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virsh create fails with "Unable to find any firmware to satisfy 'efi'" for aarch64 guest on macOS
by Nathan Vander Wilt 30 Nov '21

30 Nov '21

I am having trouble when I `virsh create test.xml` with an aarch64 guest on a macOS (Apple Silicon) host. I've wrestled with a variety of issues but the one I simply haven't been able to get past is this regarding the UEFI firmware: error: Failed to create domain from test.xml error: operation failed: Unable to find any firmware to satisfy 'efi' This is with `virsh --version` of 7.9.0 and `qemu-system-aarch64 --version` of 6.1.0, both installed via the common `brew` tool from its main 'homebrew/core' tap. I have confirmed that the loader/nvram files referenced do exist. Running `qemu-system-aarch64 -L help` outputs two lines: /opt/homebrew/Cellar/qemu/6.1.0_1/bin/../share/qemu-firmware /opt/homebrew/Cellar/qemu/6.1.0_1/bin/../share/qemu The …/share/qemu-firmware folder does NOT exist, but symlinking it to a …/share/qemu/firmware folder which does exist does not improve the situation. I have also tried renaming the …/share/qemu/firmware folder (e.g. `mv firmware zzz-firmware`) as some notes I found led me to believe that libvirst might ignore my loader/nvram settings entirely if QEMU had the "new" firmware JSON configuration stuff there? But again no improvement…. How can I debug this further? What should I try next? thanks, -natevw --- the test.xml domain configuration I am trying --- <domain type="qemu" xmlns:qemu="http://libvirt.org/schemas/domain/qemu/1.0"> <name>test1</name> <uuid>D45FCA3E-B873-4608-A0B8-3D8529E7CFB7</uuid> <memory unit="MiB">2048</memory> <cpu mode="host-model" check="partial" /> <vcpu>2</vcpu> <clock offset="utc"/> <qemu:commandline> <qemu:arg value='-accel'/> <qemu:arg value='hvf'/> </qemu:commandline> <os firmware="efi"> <type arch="aarch64" machine="virt">hvm</type> <loader readonly="yes" secure="no" type="pflash">/opt/homebrew/share/qemu/edk2-aarch64-code.fd</loader> <nvram template="/opt/homebrew/share/qemu/edk2-arm-vars.fd">/Users/me/vm_testing/vm-test1.efi.fd</nvram> <bootmenu enable="no"/> <boot dev="hd"/> </os> <features> <acpi/> <gic version="3"/> <pae/> </features> <devices> <emulator>/opt/homebrew/bin/qemu-system-aarch64</emulator> <disk type="file" device="disk"> <driver name="qemu" type="qcow2"/> <source file="/Users/me/vm_testing/vm-test1.qcow2"/> <target dev="vda" bus="virtio"/> </disk> <interface type="network"> <source network="default"/> <model type="virtio"/> </interface> <console type="pty"> <target type="serial" port="0"/> </console> <rng model="virtio"> <backend model="random">/dev/urandom</backend> </rng> </devices> </domain>

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Fwd: Installing virtiofs drivers on Windows 11....
by Mario Marietto 30 Nov '21

30 Nov '21

Hello to everyone. I'm testing Windows 11 with bhyve and I've found an annoying problem that prevents me from completing some tasks that I'm working on. It seems that the virtio-9p driver does not work inside the Windows 11 os emulated with bhyve and maybe also with qemu-kvm. When Windows 11 is launched,I don't see the folder "mnt" mounted on the root folder of Windows 11. Below you can see which bhyve parameters I've used : bhyve -S -c 4 -m 8G -w -H \ -s 0,hostbridge \ -s 1,ahci-cd,/home/marietto/Downloads/virtio/virtio-win-0.1.208.iso \ -s 2,ahci-hd,/mnt/da0p1/Backups/OS/bhyve/Windows/win11.img \ -s 3,fbuf,tcp=0.0.0.0:5900,w=1440,h=900,wait \ -s 8,virtio-net,tap0 \ ----> -s 9,virtio-9p,sharename=/mnt \ -s 30,xhci,tablet \ -s 31,lpc \ -l bootrom,/usr/local/share/uefi-firmware/BHYVE_UEFI.fd \ vm0 Investigating a little bit more and reading from this tutorial : https://virtio-fs.gitlab.io/howto-windows.html I've realized that there should be some problem with the WinFsp <http://www.secfs.net/winfsp> - Windows File System Proxy and or with the virtiofs PCI device driver because I'm not able to enable the virtiofs service with the command used on the tutorial : C:\> sc start VirtioFsSvc it gives the error : "the dependency service does not exist or it has been marked for the elimination. I've attached some screenshots to help you to understand what's happening. Please help me,thanks. Attached screenshots : https://ibb.co/m5vm1hd https://ibb.co/Qd6TS5d https://ibb.co/3018SGd -- Mario.

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virsh blockjob $domain --abort
by Jeff Brown 30 Nov '21

30 Nov '21

Please advise: After a scheduled crontab snapshot backup of a VM it failed to do a blockcommit, and is currently writing to both the snapshot and the original QCOW2 images. (I don't think it's a bug, and suspect that I caused it by running the backup script manually while the snapshot was already running.) $ virsh blockcommit VM sda --active --pivot --shallow --verbose error: block copy still active: disk 'sda' already in active block job $ virsh blockjob VM sda --info Active Block Commit: [100 %] $ virsh domblkerror VM No errors found Running on Debian 9 (Stretch). $ virsh version Compiled against library: libvirt 3.0.0 Using library: libvirt 3.0.0 Using API: QEMU 3.0.0 Running hypervisor: QEMU 2.8.1 Now, I've read up on the probable solution, somewhat, but running $ virsh blockjob $domain --abort on this production server scares me; and I'm just asking whether it would be advisable to stop services and make a full data backup prior to doing so? It would entail taking the services offline for at least an hour. The snapshot is currently at 12GB, and according to blockjob --info the VM image is 100% in synch. Will appreciate any advice. Thank you. Best regards, Jeff

2 1

Libvirt + Debian Live = Heart Attack
by Elias Mobery 25 Nov '21

25 Nov '21

Hi everyone! I've built a Debian Live ISO with packages qemu and libvirt to run a VM in the live environment. The guest images are placed in /var/lib/libvirt/images and 2GB each. Everything works great, except for one issue. When starting a VM, libvirt automatically issues a chown command to the images, changing ownership. This results in a copy of the images being created in /run/live/overlay/rw/var/lib/libvirt/images I don't want these copies to be made but can't stop it. I've tried editing qemu.conf user/group, dynamic ownership etc. without any luck. Is there a way to STOP libvirt from changing the ownership of these images?

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Questions on device-added and device-removed events
by Han Han 23 Nov '21

23 Nov '21

Hi developers, When the guest OS is booting, the event for live attachment could be caught by libvirt, while the event for live detachment could not. Version: libvirt-7.9 qemu-kvm-6.1 Steps: Terminal 1: ➜ ~ virsh event --loop --all Terminal 2: ➜ ~ virsh start avocado-vt-vm1; qemu-img create /tmp/vdb 10M; virsh attach-disk avocado-vt-vm1 /tmp/vdb vdb; virsh detach-disk avocado-vt-vm1 vdb The outputs from terminal 1: event 'agent-lifecycle' for domain 'avocado-vt-vm1': state: 'disconnected' reason: 'domain started' event 'lifecycle' for domain 'avocado-vt-vm1': Resumed Unpaused event 'lifecycle' for domain 'avocado-vt-vm1': Started Booted event 'device-added' for domain 'avocado-vt-vm1': virtio-disk1 event 'agent-lifecycle' for domain 'avocado-vt-vm1': state: 'connected' reason: 'channel event' As you can see, the device live attachment and the device detachment are both executed when the guest OS is booting, but there is only the event 'device-added' is recorded. So my questions are: 1. Is it the expected results for the results above? 2. If so, what is the internal difference between 'device-added' and 'device-removed'? 3. I notice there is the DEVICE_DELETED event in qmp? Any relation between the 'device-removed' of libvirt and the DEVICE_DELETED of qmp?

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how to use vhost-user-vsock
by Jiatong Shen 23 Nov '21

23 Nov '21

Hello community, I am looking for a way to configure vhost-user-vsock using libvirt, but looks like it is not written in doc. How can I use vhost-user-vsock using libvirt? Thank you. -- Best Regards, Jiatong Shen

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