Question : Killed processes in state D  - uninterruptible sleep (usually IO)

I've just killed a daemon with SIGTERM and then after a few minutes of no response killed it again brutally with SIGKILL. I can see its thread in my `ps x` listing all with in state D, which my man page tells me is uninterruptible sleep (usually IO). The daemon is home-grown, and has been well behaved for the last few months.

Any suggestions what I should be looking at to get to the bottom of the problem?

Answer : Killed processes in state D  - uninterruptible sleep (usually IO)

Uninterruptible sleep issues are usually connected with SMP kernels or buggy drivers for (new) hardware.
By the way, it's not the daemon that gets hung, but the shared resource it tries to use.