As a proof point, this PDF file from Microsoft and Dell on building an Azure Private Cloud Solution:
When I attended Dellworld a few weeks back, I got a tour of the Dell Engineered Systems team who spend their days working with software vendors to design, select, build and test “racks” of Dell equipment for specific applications. Those discussion indicated that it is common to run more than 1000 virtual machines per rack when using equipment tuned/selected/tested specifically for the application in use.
If you think of VMs as a server then the arrival of containers is going to upset you even more. Bare metal servers running containers may have thousands of containers and further complicate things, containers can start/stop in less than 1 second. Consider how VLAN, IP Address Allocation, DNS and MAC Address operate when you have a few container deployments.
The Etherealmind View
Like Ivan, I would consider 1000 virtual machines to be a “rule of thumb” design minimum in 2015. As always, it depends™ on your application (and thats why we have engineered systems from VCE/Dell/HPE).
Not that it matters, the old ideas of “servers per rack” is not good design criteria anymore. VM density is the first wave of change and containers is the second wave. With containers, design is about rate of change (spawn/destruction) and automation with the container orchestration engine.
I”ve haven’t been able to find the home page for Dell’s Engineered Systems on their websites or I would link to it.