If the checkbox is unchecked, the migration shouldn't be prevented.
I think the TSC frequency shouldn't be written to the VM domain XML in
such a case and then there should be no restrictions (and no guarantees)
on the frequency.
Do you mean you can't migrate even with the checkbox unchecked? If so,
what error message do you get in such a case?
Yes, exactly.
I powered off the VM and then disabled the check and then powered on the VM again, that is running on host ov301. ANd I have other two hosts: ov300 and ov200.
From web admin gui if I select the VM and "migrate" button I cannot select the destination host and inside the bix there is the words "No available host to migrate VMs to" and going to engine.log, as soon as I click the "migrate" button I see these new lines:
2020-12-16 23:13:27,949+01 INFO [org.ovirt.engine.core.bll.scheduling.SchedulingManager] (default task-41) [308a29e2-2c4f-45fe-bdce-b032b36d4656] Candidate host 'ov300' ('07b979fb-4779-4477-89f2-6a96093c06f7') was filtered out by 'VAR__FILTERTYPE__INTERNAL' filter 'Migration-Tsc-Frequency' (correlation id: null)
2020-12-16 23:13:27,949+01 INFO [org.ovirt.engine.core.bll.scheduling.SchedulingManager] (default task-41) [308a29e2-2c4f-45fe-bdce-b032b36d4656] Candidate host 'ov200' ('949d0087-2c24-4759-8427-f9eade1dd2cc') was filtered out by 'VAR__FILTERTYPE__INTERNAL' filter 'Migration-Tsc-Frequency' (correlation id: null)
2020-12-16 23:13:28,032+01 INFO [org.ovirt.engine.core.bll.scheduling.SchedulingManager] (default task-38) [5837b695-c70d-4f45-a452-2c7c1b4ea69b] Candidate host 'ov300' ('07b979fb-4779-4477-89f2-6a96093c06f7') was filtered out by 'VAR__FILTERTYPE__INTERNAL' filter 'Migration-Tsc-Frequency' (correlation id: null)
2020-12-16 23:13:28,032+01 INFO [org.ovirt.engine.core.bll.scheduling.SchedulingManager] (default task-38) [5837b695-c70d-4f45-a452-2c7c1b4ea69b] Candidate host 'ov200' ('949d0087-2c24-4759-8427-f9eade1dd2cc') was filtered out by 'VAR__FILTERTYPE__INTERNAL' filter 'Migration-Tsc-Frequency' (correlation id: null)
On all three nodes I have this kind of running kernel and package versions: