So, I plan on deploying Minecraft servers.
Now, typically for consumers, putting your OS onto an SSD is a smart decision - boot up times are a lot faster. For a server environment though, I couldn't come up with a reason.
My logic is that the server OS won't need that much speed (I can't see it being read and written to very often). If anything, I might have server maintenance at 4am to update the server but the boot-up time would be pretty negligible (since very few people would be there to experience it.)
On the other hand, placing only the Minecraft world files on an SSD leads to a very visible impact. When the world needs to be read because a player is on the move, that's where an SSD would shine. Plus, for the end users using the Minecraft server, it's the only noticeable thing they would experience (they want a fast Minecraft server. If the server OS behind that is slow but doesn't affect MC, then there isn't a problem.)
For those who aren't very familiar with Minecraft, the server will typically read a map file as a player explores the world and will save the map from memory onto the disk when the server is shutdown or at set intervals (every 15 minutes, 30 minutes, etc.)
Would there be any performance benefits for the Minecraft servers if their OSs were put onto an SSD?
Edit: I'm running Ubuntu Server 12.04.2. The system requirements for it are low so that helps with the decision.