>can you give an example of a use of this feature that can't be >accomplished by plumbing "Local 9fs $server"?
Most obviously, plumbing a Local command can't rewrite the namespace of processes on a remote server whose /proc you are importing. It also cannot be used to make modifications targeted at a single specific running process. It is a good mechanism, and one I make use of (a set of scripts I wrote for grid resource indexing uses it heavily), but it isn't a general purpose namespace manipulation tool. Processes like service listeners started by cpurc are unlikely to have a plumber in their namespace, and starting a lot of extra plumber processes to act as namespace agents doesnt seem like a sensible approach. In the context of a user using a single machine as a self sufficient environment the plumb Local trick is probably just fine for most of their namespace manipulation needs, but the context of trying to build a larger grid where multiple machines are all providing services 'a la carte' and a single cpu may be hosting processes with widely divergent namespaces, more general and precise tools are useful. In the other post I made today I discussed a modified boot system that creates both a small self-sufficient ramdisk based environment and a standard disk-fileserver based one - being able to shift which set of resources the active processes such a machine will reference has been useful to me in making sure I can keep services available even if I need to reboot a fileserver node. Philosophically, I think that if the freedom of per process namespaces is a good thing - which I certainly believe it is - then making process namespaces as flexible and precisely controllable as possible enhances that quality. Because this modification was only done very recently, I haven't yet had time to start building some of the scripts that can make use of it - but as an example, i think a script that can 'synchronize' the namespace of two given processes by finding binds and mounts present in the ns of one but not in the other and then issuing the commands to make the target process ns match the given model would be a nice thing to have. I can supply more examples from my own usage but I'm probably already past my word quota for the day. To sum up, I think that the idea of controlling the ns of processes spread across a multimachine grid via mporting multiple /proc and using scripted tools has obvious utility for dynamic grid computing where service nodes can enter and leave the resource matrix freely. ~mycroftiv
