From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: "Daniel P. Berrangé" <berrange@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>,
Juan Quintela <quintela@redhat.com>,
Markus Armbruster <armbru@redhat.com>,
qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH RFC] migration: warn about non-migratable configurations unless '--no-migration' was specified
Date: Thu, 15 Apr 2021 18:28:22 +0100 [thread overview]
Message-ID: <YHh3trxdMQ85NRTh@work-vm> (raw)
In-Reply-To: <YHhj/bo883jJ9ocy@redhat.com>
* Daniel P. Berrangé (berrange@redhat.com) wrote:
> On Thu, Apr 15, 2021 at 05:44:02PM +0200, Vitaly Kuznetsov wrote:
> > When a migration blocker is added nothing is reported to the user,
> > inability to migrate such guest may come as a late surprise. As a bare
> > minimum, we can print a warning. To not pollute the output for those, who
> > have no intention to migrate their guests, introduce '--no-migration'
> > option which both block the migration and eliminates warning from
>
> I wonder how this is actually going to work in practice ?
>
> At the time libvirt starts a guest, it has no idea whether the guest
> is likely to need migration 3, 6, 12, 24 months in to the future.
>
> IOW, we can't use a --no-migration flag and will be stuck with these
> warnings no mtter what.
>
> Is it possible to query the migration blockers via QMP ?
It's possible to query the currently active ones, as of 6.0; from my
commit 3af8554bd068576b0399087583df48518a2a98f6 it appears in the
output of query-migrate in the 'blocked-reasons' list.
The HMP equivalent is a64aec725ea0b26fa4e44f8b8b8c72be9aaa4230 showing:
(qemu) info migrate
globals:
store-global-state: on
only-migratable: off
send-configuration: on
send-section-footer: on
decompress-error-check: on
clear-bitmap-shift: 18
Outgoing migration blocked:
Migration is disabled when VirtFS export path '/home' is mounted in the guest using mount_tag 'fs'
non-migratable device: 0000:00:01.2/1/usb-serial
Dave
> Libvirt recently introduced a new API 'virDomainGetMessages' which
> lets us report a list of human targetted message strings against
> a guest. We use it for reporting when an operation has tainted
> a guest, and also use it for reporting when a deprecated QEMU
> feature is used. We could use it to report any migration
> blockers that exist.
>
> These are visible from 'virsh dominfo $guestname' and could also
> be displayed by a mgmt application.
>
> NB, the messages are intentionally declared opaque strings, so
> mgmt apps shouldn't try to parse them. They merely know whether
> the count is non-zero for any given message class.
>
>
> Regards,
> Daniel
> --
> |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
> |: https://libvirt.org -o- https://fstop138.berrange.com :|
> |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2021-04-15 17:34 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 15:44 [PATCH RFC] migration: warn about non-migratable configurations unless '--no-migration' was specified Vitaly Kuznetsov
2021-04-15 16:04 ` Daniel P. Berrangé
2021-04-15 16:30 ` Eduardo Habkost
2021-04-15 16:40 ` Daniel P. Berrangé
2021-04-15 17:07 ` Daniel P. Berrangé
2021-04-15 17:28 ` Dr. David Alan Gilbert [this message]
2021-04-16 7:33 ` Vitaly Kuznetsov
2021-04-16 16:28 ` Eduardo Habkost
2021-04-17 9:33 ` Markus Armbruster
2021-04-19 16:42 ` Daniel P. Berrangé
2021-04-19 16:48 ` Eduardo Habkost
2021-04-19 17:11 ` Dr. David Alan Gilbert
2021-04-19 17:15 ` Daniel P. Berrangé
2021-04-19 17:17 ` Daniel P. Berrangé
2021-04-19 18:47 ` Dr. David Alan Gilbert
2021-04-19 19:32 ` Eduardo Habkost
2021-04-20 11:51 ` Dr. David Alan Gilbert
2021-04-20 13:48 ` Eduardo Habkost
2021-04-20 14:10 ` Dr. David Alan Gilbert
2021-04-20 14:15 ` Daniel P. Berrangé
2021-04-20 15:20 ` Eduardo Habkost
2021-04-17 9:35 ` Markus Armbruster
2021-04-19 7:26 ` Markus Armbruster
2021-04-19 15:46 ` Markus Armbruster
2021-04-18 15:53 ` Peter Maydell
2021-04-19 16:28 ` Eduardo Habkost
2021-04-19 16:37 ` Daniel P. Berrangé
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