The Virtualization Forum really had three highlights for me. Number one was John Humphreys Introduction, He is IDC’s primary Virtualization analyst and gave a summary of the state-of-the-art.

• His magic number for the penetration of virtualization in the data center is 20%. This seems high compared to the 5% I have heard from Gartner. My read is that IDC talks about a percentage of the servers run by enterprises that use virtualization, while Gartner’s number is a percentage of all servers.
• Mid-sized companies are really in the lead. Large enterprises have to overcome too many bureaucratic hurdles and for small companies the benefits are not tangible enough.
• Disaster Recovery is a big driver, particularly for mid-sized players who do not have a secondary data center. For them, virtualization is the first step toward full blown DR capabilities.

He had lots of other interesting things to say, but these stick out because of the networking angle that is so dear to my heart. And there is one angle for each of John’s three topics mentioned above:

• The 20% penetration confirms my own anecdotal evidence that virtualization deployments are about to hit the point where networking becomes a problem. Even at a decent sized enterprise 20% means a few hundred servers at most. That’s a number that still can be handled on one LAN. If you follow Cisco ’s recommendation 100 would be the limit, but I commonly see 200 on one LAN (fewer than if we are talking all Windows, since Windows is a lot more chatty than Linux or Solaris).
• The networking angle of John’s insight regarding mid-sized enterprises is this: if you have 20 or 30 routers, switches or firewalls, your environment is still pretty stable. I know plenty of mid-sized IT environments where people basically set up their routers and switches and only touch them again when something breaks. It’s only firewalls and VPNs that require constant attention. This changes dramatically when VMware comes in. If you virtualize one single rack that has one or two switches, you end up with at least one or two virtual switches per VMware hypervisor. So (a) you have more switches in that one rack than in your whole organization and (b) since the whole point of virtualization is flexible the network changes all the time.
• The disaster discovery experience is confirmed by every single virtualization environment I have seen. It is unavoidable that once virtualization is up and running, somebody will say “Wow, now we can replicate the whole setup easily wherever we have a bunch of ESX servers” (here in Silicon Valley the sentence typically includes some casual statistics about earthquake probability). The networking angle comes into play when the setup is actually replicated: the ESX servers are easily copied, everything is up and running in minutes and, oops, our database server is directly connected to the Internet … The one thing that is not easy to copy is the whole static configuration of switches, routers and firewalls.

I will follow up with highlights number two (the always entertaining Simon Crosby of XenSource and now Citrix) and number three (a new software product presented by HP) in my next posts.