1. A method of performing a storage operation in a distributed, deduplicated storage system, comprising: receiving at a first secondary storage computing device of a plurality of secondary storage computing devices a request from a client computing device to backup a file comprising a plurality of data blocks and stored in primary storage, wherein a first deduplication database server of a plurality of deduplication database servers is designated as a failover deduplication database server for a second deduplication database server of the plurality of deduplication database servers, wherein each of the deduplication database servers stores signatures of data blocks stored in secondary storage, wherein the data blocks stored in secondary storage correspond to data blocks stored in primary storage; in response to the request and using one or more processors, calculating a signature of a particular data block of the plurality of data blocks using a signature function; identifying the second deduplication database server as the deduplication database server assigned to store the signature of the particular data block; determining that the second deduplication database server is unavailable; and querying the first deduplication database server for the signature of the particular data block.