I got a question from a colleague Bill about data center migrations:
What is a good range of number of servers that could be migrated over a weekend? I know there a bunch of qualifiers (e.g. new kit versus “lift and shift”, amount of storage, etc.), but is there some type of answer you would give if asked?
I get asked that question a lot and my usual response is that we use an application centric approach, not a server approach. The question is how many applications can we move on one weekend. When you figure that out, the number of servers is then considered.
You are of course right, there are a number of factors that are to be considered when working out the number of applications including:
- The team size.
- The migration types involved
- The complexity of the applications
- The SLA levels
- The criticality of the applications (we do not want to move too many highly complex, high criticality applications on one weekend)
Generally, we move at a relatively slow pace for the first migration weekend, then ramp up from there. In the past, I have moved anything between 1 and 10 applications on the first weekend, moving up to between 5 and 30 applications on other weekends. I suppose the maximum for that would be 200 servers if there were 1 application component on a server and an average of about 7 components per application (it depends on the complexity of your applications).