Seperated servers or virtualization, which is more efficient?

Question

My company is hosting a few separate, but related, moderately hit, web sites. Accordingly, a production database server, staging database server, production web server, staging web server, etc are needed. My question is, should we invest in physically separate servers for each of our needs, or should we put that money together and invest in a much higher end server and virtualize all of the aforementioned servers? Which route would you guys decide on, and why? Thanks.

Answer 1

You certainly want physical separation between the development and the production servers. You shouldn't ever have to worry that something you do in dev could bring down the machine on which production is hosted. And, there are some problems in development that really require either a hard reset of the physical machine or a ludicrous work-around to avoid a hard reset.

As for production web server and production database, you're not really introducing any new points of failure by virtualizing them on the same machine, particularly if you can colocate a static version of the site on another server. For any modern web site of even moderate complexity, database failure is web site failure anyway.

Answer 2

That depends on a lot of things, here are the main considerations.

If you have a lot of servers with low to moderate usage, virtualization should generally save you money on hardware, power, and floorspace. There is a tipping point, however, based on the overhead of the VM layer itself. Honestly, you will have to experiment to find the right cost/performance balance on this. I am sure the VM vendors would be happy to help you with the math.

The downside is that virtualization creates a single point of failure. If that box fails, you have downtime for all of your servers. Having them separate makes it far less likely for everything to take a dive at once.

Answer 3

From my experience, for low or moderate usage a VM is the way to go - if you get just one very powerful server instead on several moderately powerful servers you save money, power and space and make the application faster at the same time because it's running on faster hardware.

A VM also have same another nice advantages, if the server hardware fails you can load the same VM on different physical hardware and continue running like nothing happened (you do have full backups, don't you?) and you can take a copy of the actual production server and run it in isolation on a development machine to debug those annoying bug that only appear in production.

But I would put the development (and maybe testing) servers on a different physical machine than production, you need to make sure no matter what stupid mistake you made in development it wouldn't take down the production server.