Asynchronous discovery of initiators and targets in a storage fabric

• US 10,534,541 B2
• Filed: 09/20/2017
• Issued: 01/14/2020
• Est. Priority Date: 09/20/2016
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Ish, Mark, Panda, Siddhartha Kumar, Sharma, Dileep Kumar, Bhattarai, Durga Prasad
• Primary Examiner(s): Matin, Tasnima
• Application Number:
  US15/709,681
• Publication Number:
  US 20180081558A1
• Time in Patent Office: 846 Days
• CPC Class Codes: G06F 13/4022 using switching circuits, e.g. switching matrix, connection or expansion network G06F13/4009 takes precedence
• CPC Class Codes: G06F 13/4282 on a serial bus, e.g. I2C bus, SPI bus on daisy chain buses G06F13/4247
• CPC Class Codes: G06F 2213/0026 PCI express
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays

Abstract

Method and apparatus for asynchronous discovery of processing and storage nodes coupled via an expander switch in a fabric. In some embodiments, an initiator device operates as a processing node to transfer data to and from a non-volatile memory (NVM) of a target device at a storage node. One of the initiator or target devices is activated prior to the other device. The second activated device broadcasts a discovery command responsive to the activation of the second activated device and prior to receipt of a request for the discovery command from the first activated device. The first activated device processes the discovery command to establish an I/O communication link between the first activated device and the second activated device. The discovery command may include a non-volatile memory express (NVMe) controller list, and the NVM may be arranged as one or more NVMe namespaces.

Claims

1. A method for detecting elements in a fabric, comprising:

coupling an initiator device to a target device via an expander switch, the initiator device comprising a programmable processor and associated programming stored in a memory, the target device comprising a programmable processor, associated programming stored in a memory and a non-volatile memory (NVM);

activating a selected one of the initiator device or the target device as a first activated device prior to activating the remaining one of the initiator device or the target device as a second activated device;

broadcasting a discovery command by the second activated device responsive to the activation of the second activated device and prior to receipt of a request for the discovery command from the first activated device, the discovery command routed through the expander switch to multiple additional devices within the fabric;

using the first activated device to receive the broadcasted discovery command from the second activated device;

processing the discovery command received by the first activated device to establish an I/O communication link between the first activated device and the second activated device; and

using the initiator device to transfer data to and from the NVM of the target device across the fabric via the I/O communication link.

2. The method of claim 1, wherein the initiator device generates a local map of the fabric that identifies addresses of the NVM of the target device responsive to a controller list provided to the initiator device by the target device.

3. The method of claim 2, wherein the initiator device generates the local map without reference to a centralized map of the fabric from a dedicated server that describes additional initiator devices and additional target devices in the fabric.

4. The method of claim 1, wherein the first activated device is the target device and the second activated device is the initiator device, the discovery command is a discovery request command, the target device broadcasts a discovery response command in response to receipt of the discovery request command to the initiator device, the discovery response command comprises a controller list that describes a physical configuration of the NVM, and the initiator device generates a local map of the fabric responsive to the controller list.

5. The method of claim 1, wherein the first activated device is the initiator device and the second activated device is the target device, the discovery command is a discovery response command that comprises a controller list that describes a physical configuration of the NVM, and the initiator device generates a local map of the fabric responsive to the controller list.

6. The method of claim 1, wherein the initiator device and the target device each communicate in accordance with a specification document referred to as the non-volatile memory express (NVMe) specification, and wherein the NVM is arranged into at least one NVMe namespace as an addressable block of memory.

7. The method of claim 6, wherein the initiator device establishes I/O communication links with multiple NVMe namespaces of the target device.

8. The method of claim 1, wherein the NVM of the target device comprises a combined memory space provided from a plurality of data storage devices coupled to a controller circuit.

9. The method of claim 8, wherein each of the plurality of data storage devices comprises a solid state drive (SSD).

10. The method of claim 1, further comprising broadcasting, by the first activated device responsive to activation of the first activated device and prior to activation of the second activated device, a second discovery command which is not processed by the second activated device.

11. An apparatus, comprising:

a target device comprising at least one programmable processor, associated programming stored in a memory and a non-volatile memory (NVM), the target device configured to store data to the NVM at a storage node of a fabric during an activated state of the target device, the target device further configured to, responsive to a transition of the target device from a deactivated state to the activated state, broadcast a discovery response across the fabric a first time, the discovery response comprising information that identifies a physical configuration of the NVM;

an expander switch; and

an initiator device coupled to the target device via the expander switch and comprising at least one programmable processor and associated programming stored in a memory, the initiator device configured to transfer data to and from the NVM across the fabric during an activated state of the initiator device and to, responsive to a transition of the initiator device from a deactivated state to the activated state, broadcast a discovery request across the fabric through the expander switch, the target device further configured to transmit the discovery response a second time responsive to receipt of the discovery request during the activated state of the initiator device, the target device further configured to establish an I/O communication link between the initiator device and the target device responsive to receipt, by the initiator device, of the discovery response from the target device.

12. The apparatus of claim 11, wherein the initiator device and the target device are each activated in succession to provide a first activated device and a second activated device that is activated after activation of the first activated device.

13. The apparatus of claim 12, wherein the first activated device is the target device and the second activated device is the initiator device, the discovery command is a discovery request command, the target device broadcasts a discovery response command in response to receipt of the discovery request command to the initiator device, the discovery response command comprises a controller list that describes a physical configuration of the NVM, and the initiator device generates a local map of the fabric responsive to the controller list.

14. The apparatus of claim 12, wherein the first activated device is the initiator device and the second activated device is the target device, the discovery command is a discovery response command that comprises a controller list that describes a physical configuration of the NVM, and the initiator device generates a local map of the fabric responsive to the controller list.

15. The apparatus of claim 11, wherein the initiator device generates a local map of the fabric that identifies addresses of the NVM of the target device responsive to a controller list provided to the initiator device by the target device.

16. The apparatus of claim 11, wherein the initiator device generates the local map without reference to a centralized map of the fabric from a dedicated server that describes additional initiator devices and additional target devices in the fabric.

17. The apparatus of claim 11, wherein the initiator device is characterized as a processing node in the fabric and the target device is characterized as a storage node in the fabric, the apparatus further comprising an additional plurality of processing nodes and storage nodes interconnected to the expander switch, each of the additional plurality of processing nodes comprising an additional initiator device that generates a unique local map of the fabric responsive to controller lists supplied by the additional plurality of storage nodes so that each of the unique local maps links to a different set of NVMe namespaces in the fabric.

18. A data storage device configured for discovery in a fabric, comprising:

a non-volatile memory (NVM) arranged into at least one non-volatile memory express (NVMe) namespace; and

a control circuit configured to broadcast, across a fabric, a discovery command a first time responsive to transitioning of the data storage device from an inactive to an active state and prior to receipt of a request for the discovery command from an initiator device coupled to the data storage device using an expander switch of the fabric, the control circuit further configured to subsequently broadcast the discovery command a second time responsive to receipt of the request for the discovery command from the initiator device, the discovery command comprising an NVMe controller list that describes a physical configuration of the data storage device.

19. The data storage device of claim 18, wherein the control circuit is further configured to transfer data between the NVM and the initiator device across the fabric via the expander switch responsive to NVMe access commands transferred to the data storage device from the initiator device.

20. The data storage device of claim 18, characterized as a solid-state drive (SSD), wherein the NVM comprises NAND flash.