SMC HA Failover Breaks All Engine Management Connections
Corp has an SMC HA pair: active node 10.30.0.11, standby 10.30.0.12, shared management IP 10.30.0.10; log service shared IP 10.30.0.20. The 45 managed engines were bootstrapped with management server address 10.30.0.11 and log server 10.30.0.21 (the physical active node addresses), because the installer copied the active node's address. A planned failover to .12 completes; the shared IPs .10 and .20 still answer ping. Within two minutes all engines show 'No management connection'; policy installation and log browsing fail. The team wants to restore service quickly and prevent recurrence. They have out-of-band access to the SMC nodes and to one engine's local console.
1. What is the root cause, and what evidence distinguishes it from an engine or network outage?
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The engines are configured to connect to the physical addresses of the formerly active SMC node, 10.30.0.11 and 10.30.0.21, rather than the HA shared addresses 10.30.0.10 and 10.30.0.20. When the active role moved to .12, the physical .11 and .21 endpoints stopped providing the management and log services. The shared IPs still answer ping, which shows the HA pair and network path are alive; the failure is at the service endpoint the engines were told to use. This is not an engine policy problem, because every engine lost management at the same time immediately after the failover. Check the SMC HA role, the engine objects' configured server addresses, and whether the old active node is reachable.
2. Describe the fastest safe recovery. Include what you would do if the old active node can be brought back versus if it cannot.
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If the old active node can be returned to service, fail back to .11, confirm that engines reconnect, then update each engine object's management server address to 10.30.0.10 or a DNS name that resolves to the shared IP, and update the log server address to 10.30.0.20. Install policy so the corrected settings reach the engines, then test a planned failover to .12. If the old active cannot be returned, use the one engine's local console to change its management server address to the shared IP as a pilot, confirm reconnection and policy installation, then roll the change out to the remaining engines using the supported SMC address-change procedure. Do not rebuild all 45 engines, and do not change the shared IP just to match the old configuration.
3. What monitoring and process changes would prevent a repeat?
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Standardize on the HA shared IPs or stable DNS names in every engine object, not physical node addresses. Document the SMC HA design and include management and log server addresses in the build checklist. Add alerting for 'engine disconnected' and for SMC HA role changes, and monitor the SMC and Log Server services separately from simple ping. Test an SMC failover during a maintenance window at least quarterly and confirm that engines reconnect and that logs remain searchable. Keep out-of-band access to the SMC nodes and at least one engine console, and review backups and restore procedures so a management-plane change can be reversed quickly.