Localized device missing delay timers in SAS/SATA topology

摘要

A SAS expander includes DMD timers for each PHY so that the expander can track disconnected devices directly connected to the expander and signal a SAS controller when the DMD is exceeded. A system including such SAS expanders may reduce the load on the system controller. A controller may recognize expanders capable of tracking DMDs for backwards compatibility.

主权项

1. A system comprising:
a controller comprising:
a processor;memory connected to the processor; andcomputer executable program code configured to execute on the processor,wherein:
the controller memory is configured to store one or more Device Missing Delay timers;the computer executable program code is configured to:
identify at least one Device Missing Delay incompatible SAS/SATA expander that is not capable of tracking Device Missing Delay timers for devices directly connected to the Device Missing Delay incompatible SAS/SATA expander;instantiate at least one Device Missing Delay timer associated with at least one device directly connected to the Device Missing Delay incompatible SAS/SATA expander;identify at least one device missing delay compatible SAS/SATA expander that is capable of tracking Device Missing Delay timers for devices directly connected to the Device Missing Delay incompatible SAS/SATA expander;prevent instantiation of Device Missing Delay timers associated devices directly connected to the Device Missing Delay compatible SAS/SATA expander; andreceive signals form at least one expander indicating when a Device Missing Delay timer has expired; and at least one SAS/SATA expander comprising:
a processor;memory connected to the processor;one or more PHYs connected to the processor; andcomputer executable program code configured to execute on the processor,wherein:
the expander memory is configured to store one or more Device Missing Delay timers; andthe computer executable program code is configured to:
determining that a device has become disconnected from one or more of the one or more PHYs;start a Device Missing Delay timer associated with the at least one of the one or more PHYs associated with the disconnected device; andmaintain a representation of a current network topology while at least one of the one or more device missing delay timers is running.