Although the e0M interface and the RLM both connect to the internal Ethernet switch that connects to the Ethernet port indicated by a wrench icon on the rear of the chassis, the e0M interface and the RLM serve different functionality.
The e0M interface serves as the dedicated interface for environments that have dedicated LANs for management traffic. You use the e0M interface for Data ONTAP administrative tasks.
The RLM, on the other hand, not only can be used for managing Data ONTAP but also provides remote management capabilities for the storage system, including remote access to the console, monitoring, troubleshooting, logging, and alerting features. Also, the RLM stays operational regardless of the operating state of the storage system and regardless of whether Data ONTAP is running or not.