* Daniel P. Berrangé (berra...@redhat.com) wrote: > On Wed, Jun 15, 2022 at 05:43:28PM +0100, Daniel P. Berrangé wrote: > > On Fri, Jun 10, 2022 at 05:58:31PM +0530, manish.mishra wrote: > > > > > > On 09/06/22 9:17 pm, Daniel P. Berrangé wrote: > > > > On Thu, Jun 09, 2022 at 07:33:01AM +0000, Het Gala wrote: > > > > > As of now, the multi-FD feature supports connection over the default > > > > > network > > > > > only. This Patchset series is a Qemu side implementation of providing > > > > > multiple > > > > > interfaces support for multi-FD. This enables us to fully utilize > > > > > dedicated or > > > > > multiple NICs in case bonding of NICs is not possible. > > > > > > > > > > > > > > > Introduction > > > > > ------------- > > > > > Multi-FD Qemu implementation currently supports connection only on > > > > > the default > > > > > network. This forbids us from advantages like: > > > > > - Separating VM live migration traffic from the default network. > > > > > > Hi Daniel, > > > > > > I totally understand your concern around this approach increasing > > > compexity inside qemu, > > > > > > when similar things can be done with NIC teaming. But we thought this > > > approach provides > > > > > > much more flexibility to user in few cases like. > > > > > > 1. We checked our customer data, almost all of the host had multiple NIC, > > > but LACP support > > > > > > in their setups was very rare. So for those cases this approach can > > > help in utilise multiple > > > > > > NICs as teaming is not possible there. > > > > AFAIK, LACP is not required in order to do link aggregation with Linux. > > Traditional Linux bonding has no special NIC hardware or switch > > requirements, > > so LACP is merely a "nice to have" in order to simplify some aspects. > > > > IOW, migration with traffic spread across multiple NICs is already > > possible AFAICT. > > > > I can understand that some people may not have actually configured > > bonding on their hosts, but it is not unreasonable to request that > > they do so, if they want to take advantage fo aggrated bandwidth. > > > > It has the further benefit that it will be fault tolerant. With > > this proposal if any single NIC has a problem, the whole migration > > will get stuck. With kernel level bonding, if any single NIC haus > > a problem, it'll get offlined by the kernel and migration will > > continue to work across remaining active NICs. > > > > > 2. We have seen requests recently to separate out traffic of storage, VM > > > netwrok, migration > > > > > > over different vswitch which can be backed by 1 or more NICs as this > > > give better > > > > > > predictability and assurance. So host with multiple ips/vswitches can > > > be very common > > > > > > environment. In this kind of enviroment this approach gives per vm or > > > migration level > > > > > > flexibilty, like for critical VM we can still use bandwidth from all > > > available vswitch/interface > > > > > > but for normal VM they can keep live migration only on dedicated NICs > > > without changing > > > > > > complete host network topology. > > > > > > At final we want it to be something like this [<ip-pair>, > > > <multiFD-channels>, <bandwidth_control>] > > > > > > to provide bandwidth_control per interface. > > > > Again, it is already possible to separate migration traffic from storage > > traffic, from other network traffic. The target IP given will influence > > which NIC is used based on routing table and I know this is already > > done widely with OpenStack deployments. > > Actually I should clarify this is only practical if the two NICs are > using different IP subnets, otherwise routing rules are not viable. > So needing to set source IP would be needed to select between a pair > of NICs on the same IP subnet.
Yeh so I think that's one reason that the idea in this series is OK (together with the idea for the NUMA stuff) and I suspect there are other cases as well. Dave > Previous usage I've seen has always setup fully distinct IP subnets > for generic vs storage vs migration network traffic. > > With 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 / dgilb...@redhat.com / Manchester, UK