1. A computer-implemented method for managing storage, comprising: under the control of one or more computer systems configured with executable instructions, receiving a request to generate a placement decision for a data volume, the request describing a performance optimization of an underlying server to host the volume, the performance optimization defining an expected mix of read and write operations of the data volume; determining, from among a set of multiple servers, a subset of the multiple servers, wherein the subset comprises a plurality of available servers satisfying the performance optimization, wherein the set of multiple servers comprises at least some servers configured to perform a greater mix of read operations to write operations than other ones of the multiple servers, wherein the subset of available servers satisfying the performance optimization comprises servers with respective read to write mix configurations that have respective read to write mix tolerances such that the expected mix of read and write operations of the data volume is within the respective read to write mix tolerances of the available servers; evaluating, based at least in part on a mix of read and write operations of one or more volumes currently placed on the available servers, the determined subset comprising the plurality of available servers; generating a placement decision selecting a server to host the data volume from the determined subset of available servers, wherein the server to host the data volume is selected from the determined subset based at least in part on the evaluation of the determined subset of the available servers; and causing the data volume to be served by the selected server.