In a storage system, a disk device performs recovery and transfers read
data to a control device, and the control device judges the validity of
the recovery to prevent a transfer of erroneous data. A control device
read-accesses a disk device, and the disk device returns read data and a
recovered read error response. A control device, at the time of an
initial recovered read error, performs a retry of a similar command, and
if an error does not occur for read commands including the retry read
command, judges the data to be valid. Uncertain data (suspect data) upon
occurrence of a recovered read error is restored through disk retry, and
accurate read data can be transferred to the host.