Patent ID: 8656058

Claim:
A method for back-off retry in a single, cohesive serial attached small computer system interface (SAS) expander, comprising: routing a data transfer between an input of a single, cohesive SAS expander and an output of the single, cohesive SAS expander, wherein the single, cohesive expander includes a first SAS expander, and at least one additional SAS expander, wherein the first SAS expander is connected to the at least one additional SAS expander via at least one inter-expander link (IEL) for inter-expander communications, wherein the routing the data transfer further includes: routing a first OPEN request on a direct path through the first SAS expander to a port of a device; and routing a second OPEN request on an indirect alternate path from the first SAS expander and through a second SAS expander to the port of the device, the indirect alternate path established via an IEL connecting at least one phys of the first SAS expander for inter-expander communications to at least one phys of the second SAS expander for inter-expander communications; determining link availability between the second SAS expander and the port of the device; and upon determining the link availability between the second SAS expander and the port of the device to be a failed link or a busy link: re-routing the data transfer from the second SAS expander to the first SAS expander when the first SAS expander is available; re-routing the data transfer from the second SAS expander to the third SAS expander when first SAS expander is not available; and retrying the data transfer through the second SAS expander when the first SAS expander and third SAS expander is not available.