If you wanted to build a clustered Windows Server 2008 R2 host, how many NICs would you need? With iSCSI, the answer would be 6 – and that’s without any NIC teaming for the parent, cluster, or VM comms. That’s a lot of NICs. Adding 4 ports into a host is going to cost hundreds of euros/dollars/pounds/etc. But the real cost is in the physical network. All those switch ports add up: you double the number of switches for NIC teaming, those things aren’t free, and the suck up power too. We’re all about consolidation when we do virtualisation.
Why do we have all those NICs in a W2008 R2 Hyper-V cluster? The primary driver isn’t bandwidth. The primary reason is to guarantee a level of service.
What if we had servers that came with 2 * 10 GbE NICs? What if they could support not only 256 GB RAM, but 768 GB RAM? That’s the kind of spec that Dell and HP are shipping now with their R720 and HP DL380 Gen8. What if we had VM loads to justify these servers, then we needed 10 GbE for the Live Migration and backup loads? What if there was a way to implement these servers with fewer network ports, that could take advantage of the cumulative 20 Gbps of bandwidth but with a guaranteed level of service? Windows Server 2012 can do that!
My goal with the next few posts is to describe the technologies that allow us to converge fabrics and use fewer network interfaces and switch ports. Fabrics, what are they? Fabric is a cloud term … you have a compute cluster (the hosts), a storage fabric (the storage area network, e.g. iSCSI or SMB 3.0), and fabrics for management, backup, VM networking and so on. By converging fabrics, we use fewer NICs and fewer switch ports.
There is no one right design. In fact, at Build, the presenters showed lots of designs. In recent weeks and months, MSFT bloggers have even shown a number of designs. Where there was a “single” right way to do things in W2008 R2/SP1, there are a number of ways in W2012. W2012 gives us options, and options are good. It’s all a matter of trading off on tech requirements, business requirements, complexity, and budget.
Watch out for the posts in the coming days.