Cluster health and reliability engineering — Build the passive and active health-check system expected of a top-tier GPU cloud: prolog/epilog checks, LBNL NHC or equivalent, DCGM diagnostics, and detection of XID/SXID errors, ECC faults, PCIe errors, GPUs falling off the bus, IB/RoCE link flaps, and NCCL stalls — with automatic drain and job requeue. Slurm cluster architecture and lifecycle — Design, deploy, and operate production Slurm clusters on bare metal and VMs: slurmctld/slurmdbd high availability, slurmrestd, configless slurmd, SACK/MUNGE and JWT authentication, and rolling version upgrades on live clusters without losing running jobs.