Re: live migration is not using secondary interface
On Fri, Dec 18, 2020 at 10:42:16PM +0100, Olaf Hering wrote:
Am Fri, 18 Dec 2020 21:09:45 +0100
schrieb Martin Kletzander <mkletzan(a)redhat.com>:
> I am guessing you want to `--migrateuri`, possibly with `--listen-address`.
Not sure if I really _want_ all these extra knobs. The intent is clear and obvious, the
connection needs to go to the specified host and/or IP address.
But I will read through migration.html, hopefully it has some hints why this has to be so
complicated.
The thing is that there are multiple connections being made (unless you use
tunnelled migration) between the client and hosts (or hosts between themselves
with peer2peer migration), however the connection string you are using in your
command is only specifying how should virsh (or, in case of peer2peer, the
source host) connect to the destination for the libvirt connection, not the
other connections made between hypervisors.
I agree it is not that straightforward. We could default to listening on the
ip/host in the libvirt connection, however there are various setups that could
break by this and the need for more knobs would not go away anyway.
Migration is very complicated thing when you need to handle many special cases.
Believe me when I say that libvirt makes it *way* easier than what is happening
under the hood despite how many knobs it offers. If you have anything else than
the most basic setup you might need to make the extra step.
One thing to add, though. If you would rather configure the destination in a
way that its hostname resolves to the IP you would prefer for the migration it
might be enough to make this work the simple way around.
Hope that helps,
Martin
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