Maximize Virtual Machine Density per Physical Server

Before virtualization, IT would run one application per physical server so cost-per-server was a quick way to compare costs—it was a one-to-one relationship.

But once you virtualize, many applications (each in its own virtual machine) run on each physical server—it is now a many-to-one relationship. So cost-per-server comparisons no longer make sense. A much more accurate metric is cost-per-application because you want to know how much it costs to run the entire set of applications required to maintain business operations. To illustrate with an analogy, it is like asking: “Which is more cost-effective, a 4-door sedan or a 50-passenger bus?” The sedan may cost less upfront, but if your requirement is to transport a football team, then the 50-passenger bus is clearly more cost-effective! The cost-per-passenger is much lower because the bus has a higher passenger-per-vehicle density. Density matters in a many-to-one relationship.

VMware has invested in technologies to achieve very high VM density on ESX.

• Memory Oversubscription - More efficient use of physical RAM by reclaiming unused physical memory and consolidating identical memory pages among VMs on a host.
• Direct Driver Model - VMware ESX can achieve very high I/O throughput and can handle the I/O requirements for more VMs simultaneously requesting hardware resources.
• DRS with Resource Pools - Dynamically load balance VMs across a cluster so applications get required resources when they need them -a “safety net” that lets administrators run individual servers at higher utilization levels while meeting service level agreements.
• High Performance “Gang” Scheduler- Can account for CPU and I/O needs of virtual machines by dynamically allocating more resources and larger processor time slices to VMs.
• Support for Large Memory Pages and Nested Page Tables - Optimize memory access and can provide substantial performance benefits for mission critical, memory-intensive applications, can reduce CPU resource consumption by up to 15%.

No other virtualization platform achieves the high virtual machine density of VMware vSphere / ESX and still maintains consistent, high application performance across all running virtual machines. Virtual machine density per host (number of concurrent VMs that can run on a physical server) directly affects cost-per-application.

As you’ll see in the example below, the VMware solution can virtualize 100 applications at a much lower cost-per-application.

Being able to run your applications on fewer physical servers directly affects your bottom line by dramatically reducing hardware, software, power, cooling, and datacenter space costs

Don’t be misled by other virtualization vendors claiming they are “free” and less expensive than VMware. They base these claims by only looking at one factor: license price comparison. Such comparisons are over-simplified, and misleading. Run your own comparisons with your own numbers using the VMware Cost-Per-Application Calculator.