A reader sent me this question:

My company will have 10GE dark fiber across our DCs with possibly OTV as the DCI. The VM team has also expressed interest in DC-to-DC vMotion (<4ms). Based on your blogs it looks like overall you don't recommend long-distance vMotion across DCI. Will the "Data Center trilogy" package be the right fit to help me better understand why?

Unfortunately, long-distance vMotion seems to be a persistent craze that peaks with a predicable period of approximately 12 months, and while it seems nothing can inoculate your peers against it, having technical arguments might help.

Considering the webinars in the Data Center Trilogy package, the DCI webinar will be the most helpful, and the other two will give you plenty of background knowledge, which will also come handy when talking with the virtualization engineers.

Speaking of bundles, you might find the whole Data Center Roadmap bundle more interesting – it also includes the Data Center Fabrics and Clos (Leaf-and-Spine) Fabrics webinars.

Continuing with the questions from the same email:

Does the "Load Balancing and Scale-Out Application Architectures" webinar come with the DC trilogy package?

Yes, it’s part of the Data Center 3.0 webinar.

Lastly, I'm thinking even if latency and bandwidth were a non-issue with 10GE DCI, we'd have other DC-to-DC vMotion issues (e.g. asymmetrical routing, traffic trombone, firewall and load balancer state issues, storage/LUN implications, etc), correct?

Absolutely, and then there’s the danger of split subnets. Unfortunately, as we cannot ignore bandwidth and latency, we have to deal with data gravity challenges, and the overall impossibility of moving huge amounts of RAM VMs use (even in a small-to-medium data center) across a WAN link.

Oh, and finally, don’t forget that DC-to-DC vMotion might not have any real underlying business need, but appears as a requirement simply because other people want to make their lives easier, while forcing you to make the network less stable.

More information

• You might also want to read everything I wrote on vMotion in the last 5 years;
• An upcoming webinar will cover active/active data center designs; at that time I’ll add a related chapter in the Data Center Design Case Studies book;
• We can always organize an online session with your virtualization or application teams to discuss the viability of long-distance vMotion and other disaster recovery solutions. It’s amazing how much progress you can make once people start talking with each other.