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Dec 15 2008   3:34PM GMT

Focusing on the consolidation ratio in planning virtual environments



Posted by: Rick Vanover
Rick Vanover, VI3, Virtualization, VMware

Recently, myself and other bloggers as well as the editorial staff at TechTarget were invited to a briefing on Hyper-V. Microsoft is, on all fronts, trying to get Hyper-V and the Microsoft System Center technologies into the hands of administrators, and to some extent it is working.

During this briefing there was some discussion about the memory overcommit technology of VMware’s ESX, not available in Hyper-V. This feature pretty much answers my question on where I put my virtualization environment. Microsoft said IT managers and administrators won’t make their platform decisions based on one specific technology feature such as memory overcommit. I could not make sense of that answer, so I chewed on it a little and came up with this.

Managers and administrators do make their platform decisions on factors like the consolidation ratio, which is the number of guest virtual machines that are running on one physical host. In the case of VMware versus Hyper-V, there is no question which is going to perform better in achieving a higher density of guests per host. This ratio is made almost entirely possible by the memory overcommit technology that ESX has. To that end, how important is a consolidation ratio? Granted there are many factors that go into the workload and various planning tools that can be used to map out the virtual landscape, but for me, I can’t think of a more important measurable in architecting a virtual environment.

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Mwmcclure  |   Dec 16, 2008  5:57 PM (GMT)

…but would you seriously put your enterprise applications in an environment where you cannot guarantee the performance? I can see using over commit to potentially consolidate low-end applications where the uptime and performance isn’t important.

The feature fight that VMWare keeps throwing up as FUD against Hyper-V is interesting when you consider things like VMotion. Yes, you can move an application in the middle of the day with milliseconds of transition time… but would you? Microsoft obviously sees VMotion as a customer need as well since LiveMotion is on the roadmap, but how often would a sane IT Admiinstrator use these toys outside of an actual emergency?


 

MikeDiPetrillo  |   Dec 17, 2008  7:45 PM (GMT)

“how often would a sane IT Admiinstrator use these toys outside of an actual emergency”

Are you serious about this? The vast majority (80% at last count) of VMware’s 120,000+ customers use VMotion all the time every day of the week. I suggest you go post a few questions in the VMware forums (the best place for active VMware users) to see how many people use VMotion all throughout the day. Your statement is either just ignorance on your part or you’re the one throwing FUD (the fear part especially).

“but would you seriously put your enterprise applications in an environment where you cannot guarantee the performance? I can see using over commit to potentially consolidate low-end applications where the uptime and performance isn’t important.”

Uh, overcommitting resources is what you’re doing when you virtualize and consolidate. You overcommit the number of virtual CPUs versus physical CPUs. You overcommit the number of virtual NICs versus physical NICs. Overcommitting memory is now different. As long as the technology is sound and doesn’t impact performance then it’s just as good as the other parts. Most customers out there overcommit today. A survey of VMware customers showed the average overcommit of 1.8:1. A completely independent survey on Tech Target showed most people overcommit in production. Again, this just shows your complete lack of understanding of what virtualization is and the value it delivers.

NOTE: I work for VMware as a Principal Systems Engineers. I’ve been helping people go virtual for 7 years. The opinions expressed herein are my own.


 

Rick Vanover  |   Dec 17, 2008  7:51 PM (GMT)

Mike: I agree with your comments, and thank you for posting here.

I consider myself a sane administrator, and have done 6022 migrations in one year. I also consider my VI3 installation very successful.
I am doing overcommit in the 3:1 range very happily.


 

Mplatsis  |   Dec 24, 2009  12:26 AM (GMT)

is this guy serious? He obviously has no appreciation of the POWER of VMware and the PROVEN capabilities of it’s products in PRODUCTION environments!

HA/DRS are exactly the features customers ARE asking for to AUTOMATE the management and load of their VM farms and not having to pay an admin to manually do it for them.

My latest customer, 4000 LIVE migrations later, is extremely happy!

Michael Platsis
VCP3, VCP4, MCSE, CCA, PRINCE2