Layers of server monitoring
OS layer: CPU, memory, disk, network. Application layer: database, web server, application services. Hardware layer: power, fans, temperature, voltage.
Hardware health monitoring
BMC/IPMI: reach the management controller for hardware telemetry. Redfish: the standardized modern hardware management interface. SNMP: the legacy hardware monitoring approach. Key advantages: catch hardware issues before the OS goes down, predictive maintenance, unified management across vendors, and lower MTTR.