Dvorak wrote an interesting piece called "Don't Trust the Servers".
The danger of putting your data at the mercy of a company's servers was made apparent when Microsoft's own WGA servers crashed over the weekend.
I'm a big believer in redundancy and having critical items under my control. Because putting your faith in some web service to be there 24x7 just is asking for trouble. At least for mission critical items. When Skype went away I was miffed because I couldn't talk to my brother in the U.K. for a day, but pity the businesses built around Skype.
But they don't make your life any easier. A couple of weeks ago I contacted SalesForce.com because I wanted a copy of my data. I have a backup Sugar CRM system running on a server and figured that if anything happened I could spend a couple of hours and bring up the system. So I got the "trust me" email.
We actually backup all of your data for you.
If you still want to do your own backup, you
can either do a data export of your reports to
excel (in the reports tab) or you can request
a weekly data export of all your account
information for an additional $600 per year.
Oh, that's wonderful. For only $600 I can get my own data I put into the system, back to me. Inspires confidence, doesn't it?
When building systems I always look for the single point of failure. And in the case of SaaS where they hold your data in silos it's a massive single point of failure.
Moral of this story, when you're designing your system ask yourself what happens to your customers if you suddenly went away for a couple of days.