Patent ID: 7146448

Claim:
A storage controller, for providing fault-tolerant access to storage devices for host computers, comprising: a backplane; a first hot-pluggable field-replaceable unit (FRU), coupled to said backplane and having an input/output (I/O) port configured to receive from the host computers I/O requests to access the storage devices; and second and third hot-pluggable FRUs, each coupled to said backplane and having a microprocessor, wherein said second FRU is initially configured to process said I/O requests received by said I/O port, wherein said third FRU is configured to detect that said second FRU has failed and in response to process said I/O requests subsequently received by said I/O port, wherein said third FRU processes said I/O requests subsequently received by said I/O port in response to detecting that said second FRU has failed only if said third FRU microprocessor previously received user input specifying same.