On Thu, 4 Apr 2019, 20:54 Michal Skrivanek, <michal.skriva...@redhat.com> wrote:
> > On 4 Apr 2019, at 09:45, Yedidyah Bar David <d...@redhat.com> wrote: > > > >> On Thu, Apr 4, 2019 at 9:02 AM Dan Kenigsberg <dan...@redhat.com> > wrote: > >> > >>> On Wed, Apr 3, 2019 at 5:55 PM Dominik Holler <dhol...@redhat.com> > wrote: > >>> > >>> Hello, > >>> would you help me to understand if the dhcp client in an oVirt guest > >>> should refresh his dhcp configuration after the guest is resumed? > >>> If this is the case, how this should be triggered? > >>> > >>> The reason why I ask is, that if a VM suspends on a first host, and > >>> resumes on a second one, libvirt's nwfilter losses the IP address of > >>> the guest, which means that the guest is not reachable until he > >>> refreshes dhcp config, if the clean-traffic filter with > >>> CTRL_IP_LEARNING=dhcp is used. > >> > >> Do you know if libvirt's nwfilter transfers the IP address during live > >> migration? I'd suspect that you'd have the same problem there. > > AFAIK we don’t have that problem > > >> I believe that libvirt should handle this in BOTH cases (live > >> migration and suspend/resume). It should store the learned IP in the > >> suspended data and revive it on the target host. > > What about potential conflicts? > I'm not sure which conflicts you refer to. We assume that all cluster hosts have access to the same L2 network and hence a single dhcp server. > > > > Not my expertise, but regardless of the below :-), I agree with you. > > > >> Calling in +Laine Stump for his opinion. > >> > >> Regardless of this, I think that a guest should request a dhcp renewal > >> upon resume. After all, it may have been suspended for few years. > > > > I think most, if not all, dhcp clients, would renew, once they > > realized that time passed by (which is a non-trivial, but different, > > issue), > > We resync time on resume. Libvirt was supposed to do that but we were > not able to convince them, so it’s in vdsm now > > > if their lease expired. I think Dominik's question was > > about the case that the lease was _not_ expired. > > > >> This can be done if we add a "resumed" notification to the guest > >> agent, and have libvvirt/Vdsm trigger after resume. > > We have guest side hooks. Only in ovirt-ga > Does it already have one for post-resume? > > > > That's also just fine for me. I very briefly looked at all relevant > > agents (ovirt, spice, qemu) and didn't find 'dhcp' in any of them. > > So I agree it makes sense to file an RFE on one of them for this. > > qemu-ga most definitely. We do not have ovirt-ga in el8 and we do not > plan to add any new features to it. > > Thanks, > michal > > > However, we can't always rely on this - the agent might not be > > available, etc. > > > >> > >>> This scenario might happen in OST basic-suite-master and > >>> basic-suite-4.3 in verify_suspend_resume_vm0. > >> > >> I suspect that we can work around this bug in OST by requesting Engine > >> to resume vm0 on the same host it was suspended from > > > > And also, for this very specific use case, to simply have much > > shorter leases. It seems like we currently use dnsmasq's default, > > which is one hour. I guess setting it to even 2 minutes won't do > > much damage, but of course this needs testing. > > > > Best regards, > > -- > > Didi > > _______________________________________________ > > Devel mailing list -- devel@ovirt.org > > To unsubscribe send an email to devel-le...@ovirt.org > > Privacy Statement: https://www.ovirt.org/site/privacy-policy/ > > oVirt Code of Conduct: > https://www.ovirt.org/community/about/community-guidelines/ > > List Archives: > https://lists.ovirt.org/archives/list/devel@ovirt.org/message/J5EV5YCMV67XZDIPE3EPR67FBNF62OCI/ >
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