Node Boot Device Failure After an Unclean Power Loss
A four-node VxRail cluster at a distribution center loses utility power. The UPS runtime is insufficient, and all hosts power off uncleanly. On restart, three hosts boot, but node 4 fails to boot because its boot device is not detected. The vSAN datastore mounts, but several VMs are inaccessible and vSAN health shows degraded components. The customer has a four-hour RTO, no spare node on site, and a support contract with four-hour parts. Node 4's iDRAC is reachable and shows a predictive failure on the BOSS device. The customer wants to remove node 4 from the cluster immediately to clear alarms and force-mount the inaccessible VMs. The cluster uses vSAN FTT=1 RAID-1, has no stretched cluster or witness, and has backups that would take six hours to restore.
1. What should be checked before removing node 4, and why is immediate removal risky?
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Before removing node 4, establish whether the cluster can still tolerate another failure. Check vSAN health, object accessibility, and whether a rebuild is already running; a four-node FTT=1 RAID-1 cluster with one host down is degraded but may still serve data. Removing the failed host immediately can abort rebuild, reduce fault domains, and make objects non-compliant; if a second host then fails, you risk data loss. Force-mounting inaccessible VMs is worse because it can cause split-brain or corruption. Confirm the failure is isolated to node 4's boot device via iDRAC, check the other three hosts' health, and verify backups. Do not delete the host from vCenter or vSAN until you understand the object state.
2. What recovery path meets the four-hour RTO without a spare node?
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Use the four-hour parts contract for the BOSS device, not a cluster removal. Replace the failed boot device, reimage node 4 with the correct VxRail image and version, and rejoin it to the cluster through the supported VxRail procedure; vSAN will rebuild components. In parallel, identify VMs that are inaccessible and, if they are critical, restore from backup rather than force-mount. If the node cannot be recovered within the RTO, engage Dell for the supported node replacement workflow; do not manually evict the host from vSAN unless support directs it. Keep the remaining three hosts stable: avoid maintenance mode, avoid unnecessary resync load, and monitor capacity.
3. What post-incident changes prevent recurrence?
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Add UPS or generator runtime for the full cluster, document and test the VxRail and vSAN graceful shutdown and startup order, monitor boot-device health and predictive failures, verify backups and restore times, and add a 'do not force-mount' rule to the recovery runbook. Also review why the UPS runtime was insufficient and whether the cluster should have been shut down earlier. If the recovery depended on a four-hour parts contract, document that dependency and consider an on-site spare boot device for critical sites.