Ethan Banks of The Peering Introvert comments:
When researching data center network architectures, you will find the terms “scale out” and — rather less frequently — “scale up” used. What do these terms mean?
I’m going to discuss these terms in a networking sense. If you search, you’ll find that applications and storage also have concepts of scaling out vs. up. Those other areas use the terms in similar ways, although the specifics are different.
Great overview of scaling from Ethan. Both are not created equal. And one is much, much harder than the other.
Read more at: What does “scale out” vs. “scale up” mean?