1. A computer-implemented method for managing storage, comprising: under the control of one or more computer systems configured with executable instructions, receiving information about a grouping relationship between a first storage volume stored on a physical storage of a storage server and a second storage volume stored on a physical storage of another storage server, the grouping relationship indicating a level of shared infrastructure for infrastructure shared by the storage server serving the first storage volume and the other storage server serving the second storage volume, wherein the physical storage of the storage server is local to the storage server and the physical storage of the other storage server is local to the other storage server and the physical storages of the storage server and the other storage server are separate from one another; determining, based at least in part on the grouping relationship, at least one restriction for a placement decision for relocating the first storage volume to a new storage server, wherein the at least one restriction requires that after the first storage volume is relocated to the new server, the new storage server and the other storage server for the respective first and second storage volumes will have a lower level of shared infrastructure than the storage server and the other storage server currently storing the respective first and second storage volumes; generating a placement decision identifying one or more available storage servers currently serving one or more other storage volumes from a set of available storage servers to serve the first storage volume that satisfies the at least one restriction, wherein the one or more available storage servers each comprise respective local physical storages that are separate from one another and separate from the physical storage of the storage server and separate from the separate physical storage of the other storage server; and transferring the first storage volume to the one or more available storage servers identified in the placement decision, wherein transferring the first storage volume to the one or more available storage servers comprises moving data of the first storage volume from being stored on the physical storage of the storage server to being stored on the respective local physical storages of the one or more available storage servers identified in the placement decision.