In particular embodiments, a system for managing a virtualization environment includes host machines, each of the host machines including a hypervisor, user virtual machines (UVMs) and a virtual machine controller. The virtualization environment also includes virtual disks comprising a plurality of storage devices, and being accessible by the virtual machine controllers. The virtual machine controllers conduct I/O transactions with the virtual disks. The system stores an entity-relationship graph representing elements in the virtualization environment. Each of the elements is represented by an entity-type node in the entity-relationship graph, and relationships between the elements are represented by edges between the nodes.