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Virtuozzo KVM: Lower TCO than Free CentOS KVM

Sergey Maximov

Technology Corner

BackupContainersKVMReadyKernelTCOVirtuozzo 7

Open source virtualization is supplying the power for even the biggest corporations, but is KVM really as free as it seems? In this post, we explore the scenario of building your own solution, and how much you can save by utilizing the Virtuozzo KVM.

Open source virtualization is very successful these days- KVM is powering workloads for even the biggest corporations like Apple and Intel. As little as three years ago, this success may have been considered very improbable, however today KVM continues on with the quest to conquer the VM world.

As an open source project, KVM is considered free, but this is a common misconception. When calculating the overall costs for a virtualization platform the cost of hardware, support and maintenance, backups, etc… must also be factored in. Let’s take a closer look.

What choices would you make if you were building your own solution? Let’s use the example of a CentOS7 KVM (hereafter referred to as “generic KVM”) running 10K virtual servers with 2 vCPUs containing 4Gb of RAM each. Note: This article won’t dive into the differences between the Virtuozzo optimized KVM and a generic KVM.


The first thing you’ll want to figure out is hardware costs. In this example, we’ll use Dell server hardware: a Dell PowerEdge R730 (12C/24T, 384GB DDR4 RAM, 10GbE NIC, 2U). The estimated cost of a single server is about $10K USD, and assuming there is no memory over-commitment on CentOS7, each of these servers is capable of running 96 virtual machines. Virtuozzo KVM uses an advanced memory management component which allows it to achieve on average a 40% greater density than the generic KVM open source version. As a result,  running a fleet of 10,000 virtual servers would require 75 servers with the Virtuozzo KVM, and 105 servers with a generic KVM.

Assuming a depreciation period of 3 years, each year of hardware will cost you:

  • $360K USD for the generic KVM
  • $255K USD for the Virtuozzo optimized KVM

You will also have to keep in consideration the amount you’ll pay for datacenter space and utilities. With Virtuozzo, you’ll need a 150 server unit rack capacity, and for the generic KVM you will need 210, since each server is a 2-unit model. A rough and optimistic estimation of unit costs including electricity, cooling and datacenter space for the above is $40 per month. This would make your overall annual datacenter costs $100K for the generic KVM vs. $72K for a Virtuozzo KVM installation. Network bandwidth is 1 mbps for 5 instances and will cost you $5. This means your yearly network costs will be about $120K.

In summary, the aggregated hardware cost per year is:

  • $580K for the generic KVM
  • $450K for the Virtuozzo KVM

In this example, the lower instance density that is associated with the generic KVM amounts to an additional cost of $130K per year. Of course, Virtuozzo does have a licensing cost, and the retail price of that is $120 per month for a two CPU node.  This brings the total licensing cost to $110K per year. However, in this example the Virtuozzo licensing costs are less than the extra hardware bill. And, as an added bonus, Virtuozzo licensing also includes system container functionality, a technology that can further increase density and lower your costs. Volume discounts are also given (for example: a server volume of 50+ units). If you are considering a bulk order, please contact our sales team to discover all the purchasing options available to you.

Additional Services and Support

Wait-there’s still more costs to take into consideration? Yes there are- the most affordable backup solution will come in at $6 per node monthly and $7.5K per year. Patching your hosts without rebooting is about $4K per year. Maintaining an application catalog and the most popular OS images will cost about $50-100K per year. Virtuozzo has a standard, built-in backup solution for KVM- ReadyKernel. This solution provides rebootless updates and a full set of the most popular OS images, as well as more than 130 open source applications.

However, the most expensive cost factor is the consideration that must be given to support. To maintain an upstream based solution, you will need about 3 engineers for every 10K instances. Virtuozzo provides first class support from experienced industry experts, and you’ll only need a single engineer to keep your virtualization platform running.

Overall on top costs for additional software and engineering:

  • $360K for the generic KVM – 3 engineers and additional software costs
  • $100K for the Virtuozzo KVM solution – 1 engineer and no extra cost for the included features

In summary, the total cost of ownership for virtualization is:

  • $940K USD for a generic KVM
  • $655K for the Virtuozzo KVM solution

Free, open source CentOS KVM costs more than 40% more than Virtuozzo KVM.

Build or Buy

In theory, it’s possible to be an expert on KVM, and build a similar version in-house. However, you’ll first need to find a team of experienced kernel developers and budget more than a years’ worth of time to build a similar solution. Development costs are enormous, and your delayed entry to the market must also be taken into account.

During this same timeframe, you could be taking advantage of the release of numerous improvements and major updates from the team here at Virtuozzo.

There’s certainly no single right answer when putting into consideration whether to build or buy, and every organization needs to figure out what’s best for them.  When pondering that decision and performing an evaluation, it’s critical to compare not only your development costs and release schedules, but also what other new innovations your team could be focusing on.  This shift in focus could drive your business revenue, instead of having to spend your time and resources catching up with competing virtualization platforms.