Among other things, in one aspect, in general, a system for managing data in a data storage system includes a plurality of index nodes each storing a map of entries, each entry of the map including an identifier corresponding to a particular portion of data stored in the data storage system, and metadata indicating a location where the particular portion of data is stored in the data storage system, and one or more supernodes configured to return an identification of an index node that recently submitted a request for a particular identifier associated with at least one of the portions of data.