I implemented this "disk queue" system, and found it very slow, even using a memory-based /tmp filesystem (on Solaris 2.6). I could only process about 200 flows per second, as opposed to the ~1,000 per second that should be gathered. That's a pretty extreme backlog-- I don't know if I would even be able to consume it during offpeak times. I didn't really see a slowdown in gathering when the "processor" was running, though, something I wondered about when writing to disk.