Why Don't You Upgrade in Place?

Ask a senior-level SQL Server or Windows administrator about doing in-place upgrades and you’ll likely get a negative response ranging from « that’s a bad idea » to a puzzled look and a polite scoff. To someone with less experience or a higher-level view building a new server plus a migration seems both more expensive in both time and money as well as more risky than the in-place upgrade. Taken together, that sure seems like the topic for an interesting discussion. I’m betting that you already have a well-formed opinion!

Let’s start with why. Why do we need to upgrade? If it’s