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Since we have a slightly different behaviour in CentOS vs Ubuntu when it comes to hostnames, we get conflicts in the Openstack Placement service when the reinstalled node tries to start nova-compute. In CentOS, servers are given its FQDN as hostname, but in Ubuntu it does not. So, when the GPU node is reinstalled with Ubuntu , and starts nova-compute, Openstack Placement will see this as a new node, and try to add it. That obviously fails, since there already is a node in the placement database with the same name/FQDN...
Luckily, we have shelved all the VMs that was running on the GPU node, so there is no allocated resources tied to the "old" node in placement. Here is what you need to do:
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