[noahnoahnoah]

(I work at 37signals, though not as a sysadmin or developer)

Just to clarify - we do have a 24/7 on-call system administrator who is the first line of defense for when things go wrong. They're the ones who get phone calls when things do go 'bump' in the night, and they're fantastic in every way.

Our "on call" developers fix customer problems; rarely do these arise suddenly in the middle of the night, but our software has bugs (like most pieces of software) that impact customers immediately, and we've found it helpful to have a couple of developers at a time who focus on fixing those during business hours rather than working on a longer term project. Most companies probably don't call this "on call", but rather something like (as a commenter on the original post pointed out) "second level support". This is what Nick was describing in his post.

Of course, fixing root causes is the best way to solve bugs, and we do a lot of this too. We've taken a significant dent (>= 30% reduction) out of our "on call" developer load over the last 6-12 months by going after these root cause issues.

Hope that clarifies the situation some.