I support publication of this draft as an author.

Here are a couple of follow-ups to Dale's VM-related comments:

>    2.2 VM Live Migration Event
>
> If we've initiated a migration from hypervisor 1 to hypervisor 2, before it 
> is finished,
> can we initiate a migration from hypervisor 2 to hypervisor 3?  That is, does 
> the CP
> have to support chained migrations-in-progress?
> [yz] I guess the tricky point is how the VM migration is supposed to react in 
> this case.
> Will it be something like "abort and revert 1st migration and jump to the 
> migration to
> hypervisor 3" or "finish the first migration gracefully and perform the 
> second one
> immediately"?
> I do not think split-NVE control plane is necessarily to tell the difference 
> or provide
> different functionalities for them. VM migration mechanism should take care 
> of it.
> [/yz]

I agree, and would also answer "no" to Dale's original question.  Trying to 
chain or pipeline two live VM migrations complicates what has to happen in the 
brief period when VM execution is suspended to sync up the final memory changes 
and transfer execution to the destination hypervisor.  Aborting or completing 
the first migration before trying another is the only sane approach.


> From the split-NVE point of view, is there any difference between

> Paused and Suspended?

>

> [yz] No difference. Sub-section 2.4 just tries to explain VM keeps in 
> association state in case of VM Pause or Suspension.



Actually, there is a secondary difference, as described in this text in Section 
3.3, but take note of the use of "may" in the first sentence:



   A VM suspension event (discussed in section 
2<https://tools.ietf.org/html/draft-ietf-nvo3-hpvr2nve-cp-req-10#section-2>) 
may cause the relevant

   TSI instance(s) on the NVE to transit from Activated to Associated

   state. A VM pause event normally does not affect the state of the

   relevant TSI instance(s) on the NVE as the VM is expected to run

   again soon. The VM shutdown event will normally cause the relevant

   TSI instance(s) on NVE transition to Init state from Activated state.

   All resources should be released.


Thanks, --David
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David L. Black, Distinguished Engineer
Dell EMC, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953    Mobile: +1 (978) 394-7754
[email protected]<mailto:[email protected]>
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