Hyper-V 3 Offers Unlimited Live Migrations — Kind of

After being trounced in the live migration game for many years, Microsoft has finally had enough.  For those not keeping close track of the narrative, it has gone something like this:

But it’s all about to change with the upcoming release of Windows Server 2012.  Soon, Hyper-V administrators will be able to migrate an unlimited number of virtual machines at once.  How’s that for amazing: going from one concurrent live migration in the currently shipping release to infinity — and beyond — in the next!  VMware, limited to a measly 8 concurrent migrations over 10GbE, lags far behind infinity.

A vendor that is confident enough in a platform to declare that it can handle “unlimited” scale might back up such a claim with a commensurate default configuration.  For instance, if VMware vSphere concurrent vMotion maximum is 8 for 10Gb networks, then you would reasonably expect Microsoft Hyper-V 3 to either have no limitations out of the box or at least one that is significantly higher than vSphere, such as 16.

That’s why it’s kind of odd that Hyper-V 3 ships with a default concurrent live migration limit of two:

Default live migration limit in Hyper-V 3: 2

Also note that this appears to be a per-host setting — one should refrain from speculating on what happens if source and destination hosts are configured with different limits. “Abort, Retry, Fail?” does come to mind.

It’s only a matter of time before a well-meaning Hyper-V fanboy puts this unlimited live migration claim to the test, most likely with a huge number of idle, sub-1GB virtual machines — despite the fact that the pre-release Windows license agreement forbids disclosure of any performance testing results.  Whatever the result, unless your datacenter is full of tiny VMs doing absolutely no work, it’s not much of a comparison.

In the end, making claims of  “unlimited” scalability is a sure sign of desperation — even for a multi-billion dollar corporation.

UPDATE: It turns out that someone has already pushed the limits of Hyper-V 3 concurrent live migrations.  Needless to say, the tiny, idle VMs migrated flawlessly and without violating customer SLAs.

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24 Responses to Hyper-V 3 Offers Unlimited Live Migrations — Kind of

  1. >See what works best. Then tune it. If you’re on 1 GbE, then maybe try 10 and work your way
    >down. If you’re on 10 GbE converged fabric then try something like what I did. Find the sweet
    >spot and then stick with that.

    Yeah … try that with your 5 production SAP instances and 10 Exchange modules. If they fail and people complain you can just tell them “hey hey take it easy … that’s how I do tests with my XBox at home… what’s the matter with you?”

    Massimo Re Ferre’ (VMware).

  2. NiTRo says:

    @Massimo or something like “at least we didn’t pay for that” 🙂

  3. NL says:

    Really? Aidan notes that he successfully was running 60 concurrent live migrations. You might want to try reading the article you referenced.

  4. NiTRo says:

    That’s exactly what we did, and we noticed ‘I deployed 60 * 512 MB RAM Ubuntu VMs’ not ‘I deployed 60 * 4096 MB RAM WhateverOS VMs AND starting a RAM consuming app loop to actually transfert something’. Got it ?

  5. AU says:

    looks like Aidan is getting under VMware’s skin, just like the rest of Microsoft 🙂

  6. Fernando (VMware) says:

    60 * 512MB VMs , doing nothing … a very useful reference.

    Which real application today can actually run on a 512MB VM ?

    What a joke ….

  7. tony says:

    hmm grasping at straws again are we.. I’ve done 9+ concurrently live migrations each vm was 4gigs and they were running what we see as our average cpu load, no issues were detected and we didn’t have 4x10gigs just 1×10, yes the 10gig pipe was full and things were not quite instantly done but more then fast enough for us . In another test we almost doubled that perf with infiniband based networking.

  8. thomas williams says:

    interesting how most of the comments are from VMware people .. lol … the heat is on and they don’t like it one little bit …

  9. @Thomas this isn’t about the “heat” being on or anything. I think the VMware and the MS goals are pretty different at this stage. VMware have roughly 300+K customers that are trusting their technology to run their mission critical workloads. Microsoft is trying to grasp/steal as many customers as possible from VMware and I think a good eye-catching “unlimited” on those comparison slides is a way to claim they are better. Fair enough. If they (MS) fail they don’t have too much to lose anyway.

    Simply put … it is the difference between the responsibility of flying a Boeing 777 full of passengers Vs driving your Toys-R-us electric RC car with a remote. If you crash into a wall with your toy no one will care. Try to crash a Boeing 777 and you tell me.

    I wish VMware could do the same. Would be much more fun here. Unfortunately we have customers.


  10. tonyr says:

    Only 300k customers, I’m not impressed one bit!

  11. tonyr says:

    also I’m pretty sure that number was just pulled out of your ….

  12. thomas williams says:

    Here I think you are very wrong indeed. Spin it all you like, Windows Server 2012 provides the same, if not more that what you charge a lot for. Customers know it, and they know its not a toy.

    And the flip flop on your licensing back to socket and starting to bundle products is because?

  13. jude says:

    MS folks shared this… No Live Migration between Hyper v 2 to Hyper v 3.. I think this is major drawback . I would still think to have load on Hyper V for production environment.

  14. Mark Wilders says:

    Hyper-V 3 is doing so well for us, we have decided to move back to Esx5. At least it works, and has performance you can count on. Server 2012 and Hyper-V is simply still all over the place. We recently lost all performance on a host (and all VM’s, of course) because gpupdate got its’ panties in a twist, and that server doesn’t even have any GPO’s assigned.

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