Aggregate relocation enables nondisruptive hardware maintenance during an ONTAP upgrade or controller maintenance activity. ARL moves aggregate ownership between HA partners so that storage resources remain available while a node is serviced or upgraded. FlexVol and FlexGroup are volume types and do not provide the controller-level maintenance mechanism required in the scenario. RAID-TEC protects against multiple disk failures, but it does not move aggregates away from a controller for nondisruptive maintenance. The key support concept is that ONTAP nondisruptive operations rely on HA takeover/giveback and aggregate relocation to keep data online while hardware or software work occurs. For an upgrade from an older release to a later release, ARL is central when the process requires controller reboot or hardware service without forcing client downtime. This is why ARL is repeatedly tested in support exams: it is the operational bridge between hardware service and continuous data availability. References/topics: ONTAP nondisruptive upgrade, aggregate relocation, HA pair maintenance, controller availability, and upgrade readiness.