Methods and structure for hardware management of serial advanced technology attachment (SATA) DMA Non-Zero Offsets in a serial attached SCSI (SAS) expander

摘要

Methods and structure for enhanced SAS expander functionality to store and forward buffered information transmitted from a SATA end device to an STP initiator device while managing use of Non-Zero Offset (“NZO”) field values in DMA Setup FISs transmitted by the SATA end device. The enhanced expander establishes a connection between an STP initiator and a SATA end device. The expander forwards a read command from the initiator to the end device. If NZO use is supported and enabled in the end device, the end device may return read data in any order by use of the NZO field values in multiple DMA Setup FISs. The expander is further adapted to store received data and the associated multiple DMA Setup FISs from the end device in its buffer and forwards the stored data to the initiator device. In another embodiment, use of NZO in the end device is disabled.

主权项

1. A Serial Attached SCSI (SAS) expander comprising:
a host physical link (PHY) adapted to couple with a Serial Advanced Technology Attachment (SATA) Tunneling Protocol (STP) initiator device; a target PHY adapted to couple with a SATA end device; a programmable controller adapted to establish a connection between the host PHY and the target PHY to permit the transfer of data from the STP initiator device to the SATA end device, and further adapted to enable use of Non-Zero Offset fields when the SATA end device supports use of Non-Zero Offset fields; and a control circuit adapted to store and forward data exchanged between the STP initiator device and the SATA end device over the established connection.