I do think dtrace is awesome, and would certainly not make an argument against using it. We may very well use it in the future. There was no active decision no

I do think dtrace is awesome, and would certainly not make an argument against using it. We may very well use it in the future. There was no active decision not to use it at dotCloud, our "visibility toolbox" is simply based on other tools - a combination of collectd, nagios, distributed rpc tracing, active and passive checks from the http frontends, and a decent logging setup. I'm sure you could accomplish this with dtrace and probably a dozen other tools, but I guess the same is true for every problem. At some point you just choose a tool that works and move on to the next problem.