1. A storage system for maintaining a central index for performing search requests received from a plurality of clients, the storage system comprising: a shared storage for storing a management system comprising a plurality of data containers and the central index comprising index data describing each data container in the management system, the central index comprising a content index and a metadata index, the index data comprising content index data stored in the content index and metadata index data stored in the metadata index, the index data used for performing search requests on the data containers; and a storage operating system configured for periodically updating the central index by: determining a changed data container list comprising zero or more data containers in the management system that have changed since a last update by: producing a first snapshot of the management system during a last update of the central index; producing a second snapshot of the management system during a current update of the central index; and determining a difference between the first and second snapshots, the difference comprising the changed data container list; and sending an update request to a search engine for updating the central index, the update request specifying examining only data containers specified in the changed data container list, producing updated content and metadata index data for only data containers specified in the changed data container list, storing the updated content index data to the content index, and storing the updated metadata index data to the metadata index.