Help a Scoble out. What should Robert ask in his scalability interview?

One of the cool things about Mr. Scoble is he doesn't pretend to know everything, which can be an deadly boring affliction in this field. In this case Robert is asking for help in an upcoming interview. Maybe we can help? Here's Robert's plight:

I’m really freaked out. I have one of the biggest interviews of my life coming up and I’m way under qualified to host it.

It’s on Thursday and it’s about Scalability and Performance of Web Services.

Look at who will be on. Matt Mullenweg, founder of Automattic, the company behind WordPress (and behind this blog). Paul Bucheit, one of the founders of FriendFeed and the creator of Gmail (he’s also the guy who gave Google the “don’t be evil” admonishion). Nat Brown, CTO of iLike, which got six million users on Facebook in about 10 days.


What would you ask?

Comments

[sidereal]

1) At what point in the lifecycle of your product do you start to focus on high scalability. How willing should you be to compromise performance or development time to reach it before it's strictly necessary?

2) Is true horizontal scalability ever achievable or will there always be some shared resources?

3) Is designing for scalability a reactive or proactive process?

4) Are we too eager to abandon the benefits of normalization to achieve scalability?

5) Traffic patterns, especially for smaller sites, can be extremely volatile and unpredictable. How to you design for that?

6) What's the time horizon on scalability becoming a commodity that's provided by hosting providers alongside power and ethernet?

[matt m]

How much consideration was given to scalability issues in your initial design?

What decisions, from your initial design, presented the largest hurdles to scaling?

What issues will you ensure are taken into consideration in your next version 0 design?

[Daniel J. Pritchett]

FWIW we on FriendFeed directed Scoble to the High Scalability blog several times!

http://friendfeed.com/e/ad1a6d75-56de-1139-792e-2d6fa006d839/Help-I-m-clueless-about-Web-Service/

[idont]

1) Is "Think asynchronous" a good solution or not? (Message queues, batches, etc.)

2) What is the best/worst ressource to scale and/or invest in? People, material or software design? (Regarding risk, scalability, manageability, etc.)
3) What is the best strategy:
- a- Plan and integrate solution against potential risks ASAP (less risky but costs more as you integrate solutions for problem that may never occur and you may implement a wrong solution)
- b- Fix right before the probability a risk to occur is high. (more risky but with a better understanding of the situation)

[Mark Rose]

I'm launch a Facebook application in the next couple weeks. The idea is extremely useful (and makes sense to anyone who "gets facebook") and I expect explosive growth. Taking that into account, I've architectured from the ground up with shards and scalability in mind. The question I haven't be able to answer is how quickly I'll require more hardware. Is there any kind of guideline for dealing with explosive growth?