Patent ID: 6961867

Claim:
A method to provide failover capability to a data storage and retrieval system in communication with a host computer, wherein said data storage and retrieval system comprises a plurality of data storage media moveably disposed therein, one or a plurality of host computer ports, wherein said one or a plurality of host computer ports are connected to a communication bus, one or a plurality of first data storage devices capable of reading information from and writing information to each of said data storage media, wherein each of said one or a plurality of first data storage devices is in communication with one or more of said one or a plurality of host computer ports, one or a plurality of second data storage devices capable of reading information from and writing information to each of said data storage media, wherein each of said one or a plurality of second data storage devices is not in communication with one or more of said one or a plurality of host computer ports, said method comprising the steps of: receiving by said data storage and retrieval system a drive operation from a host computer; querying by said data storage and retrieval system an allocated first data device comprising one of said plurality of first data storage devices for its operational status; operative if said allocated first data device reports a non-operational status, determining by said data storage and retrieval system if a second data device comprising one of said plurality of second data storage devices is available; operative if a second data device is not available, reporting an error to said host by said data storage and retrieval system; operative if said allocated first data device reports an operational status, executing said drive command operation; suspending said drive command operation in the event of a failure of said first data storage device; deallocating said first data storage device; disconnecting said first data storage device from said communication bus; allocating a second data storage device to execute said drive command operation, wherein said second data storage device comprises one of said one or a plurality of second data storage devices; connecting said second data storage device to said communication bus; and resuming said drive command operation.