Big or small cloud providers: does size really matter?

What's the SLA?
The final, but by no means less important, consideration is the service level agreement your provider is willing to conform to.

There's a simple methodology for evaluating an SLA:

1. Get a yellow highlighter and mark the target uptime figure. Work out the number of minutes per week/month/year the service is likely to be down, and multiply by two.
2. Get a red pen and cross out the bit that explains service credits.
3. Still holding your red pen, cross out any bits that have a guaranteed time to repair.
4. Now ask yourself if your adjusted downtime figure from the first step is acceptable. If not, don't sign up.
5. If the downtime figure is OK, ask the provider to agree that if it gets it spectacularly wrong three times in six months, you can terminate with 30 days' notice. If it says “no”, don't use it.

What I've just written probably sounds overly cynical, but actually it isn't. To take the steps in order:

1. What you care about is the downtime. Nothing else. So know what it's likely to be, and be conservative.
2. Service credits are a waste of time. When your CEO is bawling you out because his finance system is down for a week over year-end, he won't give a stuff that you're getting two months' free service.
3. Guaranteed time-to-repair figures are bollocks. Nobody can guarantee such a thing.
4. Think of the CEO and his year-end finance system outage; that is, when considering acceptable downtime, think of the worst possible case.
5. If you're getting dire service, you need to be able to get out.

Interestingly, the components of my SLA methodology fit different size providers differently. The uptime figures are far easier for a large provider to conform with, because in many cases they triple up on servers (one live, one hot standby, one staging for migrating to new software versions) and have highly available resources in all other components of the system. But on the contractual side you have a much better chance of getting a smaller provider to agree to your dire-performance termination clauses. 

Oh, and stick to your guns. I've been known to drop a $2bn supplier from an RFP process simply because the SLA was a key evaluation criterion and they insisted that its standard SLA couldn't be flexed; interestingly even though the other two $2bn+ providers said that too, they did in fact agree to be flexible.

Conclusion
It's no surprise that there's no right answer. But in general, you're going to get a more robust but less personal service from the larger providers; you'll have a far more flexible service from the smaller guys but you absolutely must be completely clear on your requirements and the levels of service you consider acceptable and, more importantly, you're likely to receive.