Hierarchical device spin-up control for serial attached devices
AssigneePMC-Sierra, Inc.
InventorsLarrie Simon Carr, Heng Liao
Life of this patent
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Abstract
A method and apparatus are provided for controlling the powering-up or spin-up of devices such as hard drives using expanders in a SAS topology. The method and apparatus provides a mechanism to coordinate spin-up control among a topology of expanders. The present invention enables an expander to both process the reception of the NOTIFY command to spin up attached devices and to propagate such command to further expanders. Hierarchical spin-up control provides an advantageous, in-band mechanism that controls the expanders within the topology to limit the total number of devices powering-up at any given time.
Claims22
A method of controlling target devices in a Serial Attached Small Computer System Interface (SAS) topology using expander primitives, said method comprising:
- setting a timer for an interval of time between power-up events of said target devices in said SAS topology;
- upon expiration of said interval of time, examining all interrupt registers associated with detectors of said expander primitives in an upstream direction;
- upon indication that any of said interrupt registers are set, declaring a power-up event;
- and
- transmitting a predetermined expander primitive command so as to control said target device in said SAS topology.
A computer program product tangibly embodied in a computer readable medium for controlling target devices in a Serial Attached Small Computer System Interface (SAS) topology using expander primitives, comprising instructions for causing a computer to:
- set a timer for an interval of time between power-up events of said target devices in said SAS topology;
- examine all interrupt registers associated with detectors of said expander primitives in an upstream direction upon expiration of said interval of time;
- declare a power-up event upon indication that any of said interrupt registers are set;
- and
- transmit a predetermined expander primitive command so as to control said target device in said SAS topology.
An expander network in a Serial Attached Small Computer System Interface (SAS) topology for hierarchically controlling target devices using expander primitives including an enable spinup (NOTIFY) command, said network comprising:
- multiple expander devices including at least a first expander and a second expander;
- said first expander capable of periodically sending said NOTIFY command from said first expander to said second expander in said SAS topology;
- said second expander capable of propagating, upon reception of said NOTIFY command at said second expander, said NOTIFY command to at least one of several other expanders if said at least one of several other expanders is present on a Physical layer (PHY) of said second expander;
- and
- said second expander capable of spinning up one or more of said target devices if said one or more of said target devices in said SAS topology are present on said PHY of said second expander.
Dependencies are inferred from the claim text.