Kb114
Emulab FAQ: Testbed Operations: How can I clear machines classified dead?
To add a machine back to the pool after it has been classified as dead, You just need to free it from the emulab-ops/hwdown experiment. There are two ways to do this:
On boss, you can run
nfree emulab-ops hwdown pc10
Through the web interface, if you're in admin mode, you will get a "Free Node" link on the node's page, which you can get to by clicking on the node's name on the experiment page for the hwdown experiment.