What Service Level Agreement is acceptable for a Free service?

TechCrunch is incensed - Incensed I tell you - that Twitter's realtime search engine was down late Sunday / early Monday:

Many believe the greatest potential of Twitter lies in its ability to perform real-time searches of various keywords. So when that functionality is delayed by some 3 hours, as it is right now, and has been throughout much of the night, with no explanation, you can imagine that users are going to get a little annoyed.

.........

Not only does this badly impact my vanity searches, but there are companies who now rely on Twitter Search to run services such as brand management. Imagine the horror Comcast must be feeling right now not being able to see my tweets constantly bitching about their crap service in real-time.

Likewise, Trending Topics is not working as it also relies on Twitter Search. So we’re being tricked into thinking people actually care about the MTV Movie Awards.

The question is "what is the correct service level for a free service"?

Firstly, its worth remembering that most "for money" service levels have grades of service - bog standard is in office hours, and it goes up from there. "Drop everything at 1 am Monday morning" tends to be on the highest priced ones usually.

Secondly, you pays for response times - From "All up in an hour" to "Best Efforts" to "48 hours to get up and running" - all these have prices - and resource costs - attached.

For a free service's planning, its hard to imagine what sort of people desperately need to use Twitter search late Sunday/early Monday (insomniac bloggers, apparently ). Its also not the sort of time that most companies are going to man up for full operations owing to cost.

Also, for a free service should you really expect the highest cost "1 hour turnaround", never mind expect it at the worst times?

Unless there is some compelling reason, no sane company will man up at its highest cost for a freebie service.

The most likely "Free" Service level we would imagine that a company can reasonably give is at "in office hours, best efforts" level. But bear in mind, that if you are paying nothing, the only service level that you have a right to expect is zero. And its most likely to be zero at those points of stress like late night weekends.

Which is why, of course, we strongly recommend one never puts anything of any value on free Cloud services.