Kb116

Emulab FAQ: Testbed Operations: How do I reserve nodes for maintenance?

There is a state that you can put nodes in, so that they won't be allocated to normal user experiments.

The easiest thing is to move them into one of the special experiments, most likely hwdown:

	nalloc emulab-ops hwdown pcXX ...

If you actually want to set up links and test interfaces, etc. then you can just create your own experiment and explicitly allocate the nodes you want in the NS file with:

	# ns: allocate a specific node
	tb-fix-node $node pcXX

of course, you will still be in a race with others to allocate the node.

If one of the nodes you want slips away and winds up in someone else's experiment you can "schedule" it:

	sched_reserve emulab-ops hwdown pcXX ...

and when the node is freed, it winds up in emulab-ops/hwdown (you can actually use any pid/eid). If you want to get it back right away, you can swapout the experiment it is currently in, and then swap them back in (after coordinating with the person of course, since swapout/in is not yet transparent: no disk state is saved).