Abstract: Embodiments of a routing device for coordinating the interoperability of devices with varying capabilities that send and/or receive commands in a storage network are disclosed. A host device in the storage network may inquire the capabilities of a storage device in a storage network. A routing device may receive a response from the storage device and pass the response through to the host unaltered or may alter the response to reflect the higher or lower capabilities of the routing device before sending the response to the host.

Abstract: Embodiments of the present invention provide a system and method for handling unit attentions. According to one embodiment of the present invention, a copy manager can receive an extended copy command and can issue a unit attention clearing command, such as the test unit ready command, to the source and destination devices listed in the extended copy command. The copy manager can further issue read commands to the source device and write commands to the destination device to copy data from the source device to the destination device according to the extended copy command.

Abstract: Systems and methods for performing error recovery in a system utilizing redundant communication links. In one embodiment, a host device is coupled to a sequential device such as a tape drive by a pair of Fibre Channel links. The host is configured to associate an identifier with each command. Upon detecting a failure of the transmission of the command via the first link, the host re-transmits the command via the second link. When the link failure is detected, the status of the last command transmitted before the failure is requested. After receiving the status of the command, a request that recovery start (possibly at a point indicated by the status information) is transmitted to the sequential device. If the recovery request is accepted, performance of the command is completed.

Abstract: Systems and methods for reducing the number of unit attentions provided to a set of initiator devices by eliminating unnecessary unit attentions from queues in which unit attentions for each of the initiator devices are stored. In one embodiment, a system comprises a processor and a memory implemented in a router that is coupled between a target device and multiple initiator devices. As each unit attention is generated by the target device, it is forwarded to the initiator device that prompted the unit attention, and is stored in a queue for each of the other initiator devices. Periodically, the queues are examined to determine whether any of the unit attentions stored therein are unnecessary. One or more of the unit attentions that are determined to be unnecessary may be eliminated from the respective queues, reducing the number of unit attentions that are provided to the respective initiator devices.