Re: [libvirt] VN-Link vNIC memory state copying on VM Migration

-----Original Message----- From: Jagath Weerasinghe [mailto:jagfoss@gmail.com] Sent: Tuesday, April 17, 2012 8:19 AM To: Christian Benvenuti (benve) Cc: libvir-list(a)redhat.com Subject: Re: [libvirt] VN-Link vNIC memory state copying on VM Migration Chris >> OK. In phase 3, the RAM used by VM in source host is copied to the >> destination. Then what about the memory state of vNIC's in the M81KR VIC. >> Isn't there any memory for traffic passing through vNICs and also for >> vNIC statistics?  What I am talking about is copying of this memory to the >> destination vNIC. > > No, that data (statistics, etc) are not copied to the dst host/vnic. > However, you can find those statistics/counters on the switch (which are > preserved across live migrations). OK. I think this operation is the same for both IEEE802.1qbh (VN-Link) and IEEE802.1qbg. Is that correct?

One more thing. Could you please tell me where the port profile association/dissociation messages of libvirt are converted to VIC protocol messages. Is this done by CNA it self?

>> > (*) See the migration parameter 'migrate-setmaxdowntime' >> > >> > In phase 4 libvirt applies the port profile to the interfaces >> > that need it and starts the VM (which had been created and put in >> > pause state in phase 2). >> > There is therefore a small period during which both VMs (the one >> > on the source host and the one on the destination host) are in pause >> > state (see dotted lines above). >> > Phase 4 will start the VM on the dst host, >> > Phase 5 will kill the (paused) VM on the src host. >> > >> > The amount of time during which both VMs are in pause state depends on >> > a number of factors, including: >> > - maxdowntime:  the smaller you configure this value and >> >                - the longer will take the migration to complete, but >> >                - the smaller the pause duration will be >> > - bandwidth available on the interface/s used to carry the migration >> >  traffic, and amount of RAM assigned to the VM (since you need to >> >  copy it) >> > - time taken to complete the port profile associations on the dst host >> >  (which depends on how loaded the switches are) >> > - ... >> > >> > >> > Hope this clarifies a bit. >> > /Chris >> > >> >> If this memory state (or traffic) is not copied and moved to the >> >> destination vNIC how the smooth communication, which is >> >> guaranteed on VM migration, is achieved? >> >> >> >> Thanks >> >> Jagath >> >> >> >> > >> >> > If you refer to port profile info, then there is no copying involved: >> >> >  the source host disassociates the vnic port profile and >> >> >  the destination host re-associates the port profile on the new vnic. >> >> > >> >> > /Chris >> >> > >> >> >> -----Original Message----- >> >> >> From: libvir-list-bounces(a)redhat.com >> >> > [mailto:libvir-list-bounces@redhat.com] On Behalf Of Jagath >> >> >> Weerasinghe >> >> >> Sent: Friday, April 13, 2012 9:16 AM >> >> >> To: libvir-list(a)redhat.com >> >> >> Subject: [libvirt] VN-Link vNIC memory state copying on VM Migration >> >> >> >> >> >> Hi All, >> >> >> >> >> >> I am new to libvirt. And want to know how the VM migration >> >> >> occurs in VN-Link (IEEE802.1Qbh). As far as I know, >> >> >> the memory state of vNICs in M81KR VIC has to be copied >> >> >> and moved to the destination vNIC on VM migration. >> >> >> Is that correct? If so, could you please tell me how this >> >> >> has been implemented in libvirt? >> >> >> >> >> >> Thanks >> >> >> Jagath >> >> >> >> >> >> -- >> >> >> libvir-list mailing list >> >> >> libvir-list(a)redhat.com >> >> >> https://www.redhat.com/mailman/listinfo/libvir-list >> >> >> >> -- >> >> libvir-list mailing list >> >> libvir-list(a)redhat.com >> >> https://www.redhat.com/mailman/listinfo/libvir-list