Data processing system with efficient path selection for storage I/O operations

摘要

A host computer dispatches storage I/O operations to a storage array by, in an I/O dispatch context, (i) identifying an I-T-L nexus based on a minimum-weight I-T nexus and a logical device of a storage I/O operation, (ii) dispatching the I/O on the identified I-T-L nexus, and (iii) updating a dispatch weight for the minimum-weight I-T nexus and logical device. In an I/O completion context, a completion weight is updated for an I-T nexus and logical device of a completed I/O. A background process is performed regularly for selecting the minimum-weight I-T nexus, including (a) for each I-T nexus, calculating a current weight value as a sum of difference values for all logical devices, each being the difference between the dispatch weight and the completion weight for the I-T nexus and logical device, and (b) selecting the I-T nexus having a minimum current weight value as the minimum-weight I-T nexus.