snapshot creation broken recently?
by Štěpán Němec
Hello,
until very recently I had been happily creating snapshots of running VMs
(created using virt-install) simply with
virsh --connect qemu:///system snapshot-create-as <domain-name> <snapshot-name>
Now when I try to do that I get the following error:
Error creating snapshot: operation failed: Failed to take snapshot: pre-save failed: qxl
Same thing trying to create a snapshot from virt-manager (which also
used to work). Here's the full backtrace (as displayed in virt-manager):
Error: Error while writing VM state: Unknown error -1
Traceback (most recent call last):
File "/usr/share/virt-manager/virtManager/asyncjob.py", line 65, in cb_wrapper
callback(asyncjob, *args, **kwargs)
File "/usr/share/virt-manager/virtManager/details/snapshots.py", line 237, in _do_create_snapshot
self.vm.create_snapshot(xml)
File "/usr/share/virt-manager/virtManager/object/domain.py", line 1124, in create_snapshot
self._backend.snapshotCreateXML(xml, flags)
File "/usr/lib/python3.9/site-packages/libvirt.py", line 3059, in snapshotCreateXML
raise libvirtError('virDomainSnapshotCreateXML() failed')
libvirt.libvirtError: operation failed: Failed to take snapshot: pre-save failed: qxl
Error: Error while writing VM state: Unknown error -1
I am on Arch Linux (x86_64), using the distro packages. Checking my
pacman logs, might update of qemu-headless from 6.0.0 to 6.1.0 have
something to do with that?
(Since then, libvirt has also been updated from 7.6.0 to 7.7.0, but I
see no change WRT the problem described.)
I would appreciate any advice on how to further investigate and/or work
around the problem.
(I checked https://gitlab.com/libvirt/libvirt/-/issues and didn't find
anything that seemed related.)
Thanks,
Štěpán
3 years, 2 months
one qustion about the snapshot of the libvirt, thanks.
by Guozhonghua
Hello,
When we test snapshot features and review the code of libvirt, there is one question, not an issue.
/* do the memory snapshot if necessary */
if (memory) {
/* check if migration is possible */
if (!qemuMigrationSrcIsAllowed(driver, vm, false, 0))
goto cleanup;
While making one snapshot with memory on one vm, but it is not allowed while the vm which has some src devices, such as pci devs, with which the vm is not allowed to be migrated.
I want to known the reason, why should it check this conditions?
Thank You!
3 years, 2 months
vm vcpu uses isolated cores
by Jiatong Shen
Hello,
I am trying to understand why qemu vm CPU threads uses isolated cpus.
I have a host which isolates some cpus using isolcpu
like isolcpus=1,2,3,4,5,7,8,9,10,11. unfortunately, vcpupin does not mask
out these cpus (vcpupin is still something like ffffffff).
When I log in to the system, seems qemu cpu thread only runs on these
isolcpus. I do not quite understand this behavior, because I think by using
isolcpu, kernel schedule will exclude these cpus and thus vcpu thread
shouldn't use these cores unless taskset explicitly got called.. So my
question is how does cpu thread got scheduled on isolated cpus?
Thank you.
--
Best Regards,
Jiatong Shen
3 years, 2 months
