vmotion

There is something I always wanted to know and that is how VMotion (yes I am using the old school name on purpose) came to life. After some research on the internet and even on the internal websites I noticed that there are hardly any details to be found.

Now this might be because the story isn’t as exciting as we hope it  will be or because no one took the time to document it. In my opinion however VMotion is still one of the key features VMware offers but even more important it is what revolutionized the IT world. I think it is a great part of VMware history and probably the turning point  for the company. For me personally VMotion literally is what made me decide, years ago, to adopt virtualization and I am certain this goes for many others.

At VMworld I asked around who was mainly responsible for VMotion back in the days but no one really had a clear answer until I bumped into Kit Colbert. Kit, who was still an intern back then, worked closely with the person who originally developed VMotion. I decided to contact the engineer and asked him if he was willing to share the story as there are a million myths floating around.

Before I reveal the real story about how VMotion came to life I want to thank Mike Nelson for revolutionizing the world of IT and taking the time to share this with me and allowing me to share it with the rest of the world. Here is the true story of VMotion:

A bunch of us at VMware came from academia where process migration was popular but never worked in any mainstream OS because it had too many external dependencies to take care of.  The VMware platform on the other  hand provided the ability to encapsulate all of the state of a virtual machine.  This was proven with checkpointing; where we were able to checkpoint a virtual machine, copy the state to another host, and then resume it.  It was an obvious next step that if we could checkpoint to disk and resume on another machine that we should be able to checkpoint over the network to another machine and resume.

During the design phase for what would later become Virtual Center a couple of us discussed the notion of virtual machine migration.  I took the lead and wrote up some design notes. I managed to extract myself from the mainline development of ESX 2.0 and I decided to go off and build a virtual machine migration prototype.  I was able to build a prototype fairly quickly because we already had checkpointing support.  However, of course there was a lot more work done by myself and others to turn the prototype into a high quality product.

I needed something to demo it so I used the pinball application on Windows.  The only interactive app I had on my virtual machines was pinball.  I had two machines side by side each with a display. I would start pinball on a virtual machine on one physical machine.  Then I would start the migration and keep playing pinball. When the pre-copy of memory was done it would pause for a second and then resume on the other machine. I would then keep playing pinball on the other machine.

That’s the VMotion story. Basically VMware had built the underlying technology that made VMotion possible.  All it required was someone to take the time to exploit this technology and build VMotion.

-Mike

The funny thing is that although this might have been the obvious next step for VMware engineering it is something that “shocked” many of us. Most of us will still remember the first time they heard about VMotion or remember it being demoed, and as I stated it is the feature that convinced me to adopt virtualization at large scale, or better said it is responsible for me ending up here! In my case the demo was fairly “simple” as we VMotioned a Windows VM, however we had an RDP session open to the VM and of course we were convinced the session would be dropped. I think we did the actual VMotion more than 10 times as we couldn’t believe it actually worked.

Now I am not the only one who was flabbergasted by this great piece of technology of course hence the reason I reached out to a couple of the well known bloggers and asked if they could tell their VMotion story/confessions…

Cormac Hogan, comachogan.com

So for me, it happened back around 2004 when I was still at EMC. I was part of a team that provided customer support for Unix and Linux platform. I had seen ESX (might have been 2.0) when someone said that I needed to see this new vMotion feature. I didn’t really get it when he said that he had just moved all the VMs from host A to host B. But when he then flicked the power button on host A, and when I saw that all the VMs were still running, then it sunk in. That was then I knew I needed to work for this company!

Truly eye opening experience, which resulted in a career change. How cool is that 🙂

Chad Sakac, virtualgeek.typepad.com

For me, while I remember being amazed from a generic bland use case, the “this is going to change everything” moment occured for me in 2007.

If vmotion is about non-disruptive workload mobility (an amazing concept), where things get crazy cool for me are scenarioes and definitions of “workload” and “mobility” are stretched.

In early 2007, I was in the basement of my house playing with early prototypes of the Celerra VSA running on ESX whiteboxes. It was one of those now-common “russian doll” scenarios where the host powering the VSA was in turn being supported by an iSCSI LUN being presented by the VSA, which in turn supported other VMs. While intellectually obvious that VMotion **should** work, it was never the less amazing to see in it action, with no dropped connection under load.

At that moment, I realized that the workload could be as broad a definition as I wanted, including full blown stacks normally associated with “hardware” like arrays. It was also an “aha” that this could transform a million use cases not normally associated with a server workload.

Ironic side note – the next day, I was showing that concept in the boardroom during a discussion why all our stacks needed to be encapsulated and virtualized. Turns out they were already working on it 🙂

That all said – those “aha moments” happen constantly. Another example – this time more recently – was about stretching the definition of “mobility”. It was during the run-up to VMworld 2010, when we were doing the demo work for the VERY long distance vMotion scenarios with early prototypes of VPLEX Geo. As we dialed up the latency between the ESX hosts on the network and storage – I was very curious to where it would blow up. When it made it past 44ms RTT (for math/physics folks – that’s the latency equivalent of 13,000km at the speed of light!), it was a “wow” moment (BTW, it blew up at 80ms :-)) I need to point out here that it completely violates the VMware support position (and for many, many good reasons – one “it worked in this narrow case in the lab” does not equal “works in the real world”), so don’t try this at home.

BUT it highlighted how, over time, the idea of non-disruptive workload mobility over what TODAY are consider crazy distances, network, and storage configs will tomorrow be considered normal.

vMotion and svMotion never cease to amaze me.

Nothing less than expected of course, some crazy scenario and as Chad states it isn’t supported but it definitely shows the potential of the technology!

Frank Denneman, frankdenneman.nl

During our VCDX sessions in Copenhagen we spoke about  things in your life you would always remember. My reply was ; Seeing  Return of the Jedi in the cinema, the falling of the Berlin wall, 9/11, Pim Fortuyn murder and witnessing vMotion in action for the first time.

I clearly remember my colleague screaming through the wall that separated our office. “Frank do you really want to see something cool?” As an MS exchange admin/architect responsible for a global spanning exchange infrastructure nothing really could impress me those days but  giving him the benefit of the doubt I walked over. Peter sitting there grinning like a madman, offered me a seat, because he thought it was better to sit down. He opened a dos prompt, triggered a continuous ping and showed the virtual infrastructure explaining the current location of the virtual machine. As he started to migrate the virtual machine he instructed me to keep tracking the continuous ping, after the one ping loss he explained the virtual machine was up and running on the other host and to prove me, he powered-down the ESX host. I just leaped out of my seat, said some words I cannot repeat online and was basically sold. I think we  migrated the virtual machine all day long, inviting anyone who passed by our office to see the best show on earth. No explanation needed of course, but from that point I was hooked on virtualization and the rest is history.

I still enjoy explaining people the technology of vMotion and it still ranks in my book as one of the most-kick-ass technologies available today. As Mendel explained in the keynote of VMworld 2006 demonstrating recording an execution stream (now FT), we have the technology and the platform available to do anything we want, the problem is we still haven’t reached the boundaries of our creativity, I fully concur and I think we still haven’t reached the full potential of vMotion.  Heck, I’m off to my lab just to vMotion a bunch of virtual machines.

Can I thank Peter for introducing Frank to the wonderful world of virtualization?

Mike Laverick, rtfm-ed.co.uk

My first VMotion was  demo of media server being moved from one ESX hosts to another – with the buffering switched off. I forget now what movie clip was being shown to the desktops – I think it might have been a Men In Black trailer. Anyway, nothing flickered and nothing stopped – the video just kept on playing without a hick-up.

At that point my mind began to race. I was thinking initially about hardware maintenance. But quickly (this in in ESX2) days began to think of moving VMs around to improve performance, and possibility of moving VMs across large distances. At the time I told my Microsoft chums all about this, and they were very skeptical. Virtualization, they (mis)informed me, was going to be a flash in the pan, and that VMotion was some kind of toy – of course, in a Road to Damascus way now HyperV supports “Live Migrate” its an integral part of virtualization. In truth when I started to demo VMotion to my students occasionally I felt like I was show-boating. This was in the vCenter 1.x days. But in some respects there’s no harm in showboating. It allowed me to demonstrate to students how far ahead VMware was against the competition, and what a visionary are company VMware is. It certainly added to my credibility to have a technology that was so easy to setup (so long as you meet the basic pre-requisites) and the great thing about VMware and the courses is that you didn’t have to “hard sell” the product sold itself.

On a more humorous note I’ve seen all kind of wacky VMotion setups. I once had two PIII servers with a shared DEC JBOD with SCSI personality cables (circa NT4 Clustering configuration) just to get the shared storage running. I managed to get VMotion working with 1997 era equipment. I’ve also been asked by student – who had laser line-of-site connectivity between two buildings – if he could VMotion between them. I laughed and said as long as he could  meet the pre-requisites there would be no reason why not. Although it would definitely be unsupported. Then I smiled and said, if he ever got VMotion working – I would come round in my Dr Evil outfit to explain – VMotion – with laser.

As I already stated, but re-enforced by Mike… VMotion changed the world, and the fact that both Microsoft and Citrix copied the feature definitely supports that claim… now I am wondering if the VMotion across “laser line-of-site connectivity” actually worked or not!

Scott Lowe, blog.scottlowe.org

I remember when I first started testing vMotion (then VMotion, of course). I was absolutely sure that it had to be a trick–surely you can’t move a running workload from 1 physical server to another! I performed my first vMotion with just a standard Windows 2000 server build. It worked as expected. So I tried a Citrix Metaframe server with users logged in. It worked, too. Then I tried a file server while copying files to and from the server. Again, it worked. SSH? Worked. Telnet? Worked. Media server with clients streaming content? Web server while users were accessing pages and downloading files? Active Directory? Solaris? Linux? Everything worked. At this point, after days–even weeks–of unsuccessfully trying to make it fail, I was sold. I was officially hooked on virtualization with VMware.

Thanks for the invitation to share memories about vMotion!

It appears that all top bloggers got hooked on virtualization when they witnessed a VMotion… As I stated at the beginning of this post; VMotion revolutionized the world of IT and I would like to thank VMware and especially Mike Nelson for this great gift! I also like to thank Scott, Mike, Frank and Chad for sharing their stories and I bet many of you are currently having flashbacks of when you first witnessed a VMotion.