A while ago I guestimated that most private clouds don’t have more than a few thousand VMs, and that they don’t need more bandwidth than what two ToR switches could provide.
Last autumn Iwan Rahabok published a blog post describing the compute- and storage parts of it, and I had a presentation describing the networking aspects of high-density consolidation. However… whenever I was talking about the high-density virtualization I wondered how realistic that scenario is in a typical enterprise environment, and you know how hard it is to get a reliable set of data points that have more statistical significance than anecdata.
- Statistics about CPU and memory configurations of real-life ESXi hosts;
- VM density statistics.
If you massage that data right, you get the conclusions I was looking for:
- Plenty of deployments have enough CPU cores and memory for high-density virtualization;
- A lot of people have high VM density on two-socket servers, and predictably the percentage increases with the number of cores.
On the other hand, it’s interesting to see that while ~15% of 24-core hosts have more than 100 VMs, almost 20% of those hosts run less than 10 VMs.
On a slightly tangential topic, I ran the presentation I mentioned above as a short webinar for my subscribers, and the resulting videos are already available in the Designing Private Cloud Infrastructure webinar.