In one aspect, a system for indexing transactions over a plurality of communication lines is described. In various embodiments, the system includes a host controller and a plurality of storage devices in communication with one another. Each of the storage devices is configured to store data. The communication lines facilitate communications between the host controller and the plurality of storage devices. A selected one of the storage devices is configured to function as a transaction indexer to monitor the communication lines and index and store selected transaction information associated with operations that occur over the communication lines. While the host controller may be arranged to configure the transaction indexer, the transaction monitoring, indexing and storing are performed substantially automatically by the transaction indexer without requiring further instructions from the host controller.