METHODS AND SYSTEMS USING SOLID-STATE DRIVES AS STORAGE CONTROLLER CACHE MEMORY

• US 20120102268A1
• Filed: 10/25/2011
• Published: 04/26/2012
• Est. Priority Date: 10/26/2010
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Smith, Gerald E., Hallyal, Basavaraj G.
• Granted Patent: US 8,938,574 B2
• Time in Patent Office: Days
• US Class Current: 711/113
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2089 Redundant storage control functionality
• CPC Class Codes: G06F 12/084 with a shared cache
• CPC Class Codes: G06F 12/0873 Mapping of cache memory to specific storage devices or parts thereof
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/222 Non-volatile memory

Abstract

Methods and systems for using one or more solid-state drives (SSDs) as a shared cache memory for a plurality of storage controllers coupled with the SSDs and coupled with a plurality of storage devices through a common switched fabric communication medium. All controllers share access to the SSDs through the switched fabric and thus can assume control for a failed controller by, in part, accessing cached data of the failed controller in the shared SSDs.

Claims

1. A system comprising:

a plurality of storage controllers adapted to couple with one or more host systems;

a plurality of storage devices for persistent storage of user data received from the one or more host systems;

a switched fabric communication medium coupling the plurality of storage controllers with each of the plurality of storage devices; and

a solid-state drive (SSD) coupled with each of the plurality of storage controllers through the switched fabric communication medium,

wherein each of the plurality of storage controllers uses the SSD as a cache memory.

2. The system of claim 1

wherein each of the plurality of storage controllers uses a corresponding portion of the SSD as its cache memory.

3. The system of claim 1

wherein the SSD further comprises:

a plurality of SSDs wherein each of the plurality of storage controllers uses a corresponding portion of the plurality of SSDs as its cache memory.

4. The system of claim 3

wherein the system dynamically adjusts the size of the portion of the plurality of SSDs corresponding to each storage controller based on a load associated with each storage controller.

5. The system of claim 1

wherein a plurality of logical volumes are configured on the plurality of storage devices by the plurality of storage controllers,

wherein each of the plurality of logical volumes is associated with a corresponding portion of the SSD, and

wherein each storage controller of the plurality of storage controllers uses as its cache memory a portion of the SSD corresponding to a logical volume accessed by a request from said each storage controller.

6. The system of claim 5

wherein the system dynamically adjusts the size of the portion of the SSD corresponding to each logical volume based on a load associated with each logical volume.

7. The system of claim 1

wherein each of the plurality of storage controllers is operable in a corresponding controller power domain of a plurality of controller power domains,

wherein the SSD, the plurality of storage devices, and the switched fabric communication medium are operable in a one or more power domains separate from the plurality of controller power domains, and

whereby, responsive to loss of a controller power domain associated with a first storage controller, the SSD, the plurality of storage devices, and the switched fabric communication medium remain accessible to other storage controllers in other controller power domains through the switched fabric communication medium.

8. A system comprising:

a plurality of storage controllers adapted to couple with one or more host systems;

a plurality of storage devices for persistent storage of user data received from the one or more host systems;

a switched fabric communication medium coupling the plurality of storage controllers with each of the plurality of storage devices,

wherein the switched fabric communication medium comprises two switching devices,

wherein each switching device comprises a solid-state drive (SSD) used to cache data received from the storage controllers in processing write requests from attached host systems directed to one or more of the plurality of storage devices, and

wherein each of the two switching devices mirrors cached data from its SSD to the SSD of the other of the two switching devices using the switched fabric communication medium.

9. The system of claim 8

wherein each switching device associates each of the plurality of storage controllers with a corresponding portion of its SSD.

10. The system of claim 8

wherein the SSD of each switching device further comprises:

a plurality of SSDs wherein each switching device associates each of the plurality of storage controllers with a corresponding portion of its plurality of SSDs.

11. The system of claim 10

wherein each switching device dynamically adjusts the size of the portion of its plurality of SSDs corresponding to each storage controller based on a load associated with each storage controller.

12. The system of claim 8

wherein a plurality of logical volumes are configured on the plurality of storage devices by the plurality of storage controllers,

wherein each of the plurality of logical volumes is associated with a corresponding portion of the SSD of each switching device, and

wherein each storage controller of the plurality of storage controllers uses as its cache memory a portion of the SSD of each switching device corresponding to a logical volume accessed by a request from said each storage controller.

13. The system of claim 12

wherein each switching device dynamically adjusts the size of the portion of its SSD corresponding to each logical volume based on a load associated with each logical volume.

14. The system of claim 8

a plurality of power domains wherein each of the plurality of storage controllers is operable in a corresponding controller power domain of the plurality of controller power domains;

and

one or more storage power domains separate from the plurality of controller power domains, wherein the plurality of storage devices and the switched fabric communication medium are operable in the one or more storage power domains, and

whereby, responsive to loss of a controller power domain associated with a first storage controller, the switched fabric communication medium and the plurality of storage devices remain accessible to other storage controllers in other controller power domains through the switched fabric communication medium

15. A method operable in a system, the system comprising a plurality of storage controllers coupled with a plurality of storage devices through a switched fabric communication medium, the system further comprising a solid-state drive (SSD) coupled to each of the plurality of storage controllers through the switched fabric communication medium, the method comprising:

receiving a write request in a storage controller of the plurality of storage controllers, the write request directed to a logical volume configured on portions of one or more of the plurality of storage devices;

caching data associated with the write request from the storage controller into the SSD; and

flushing, by operation of the storage controller, cached data from the SSD to the logical volume for persistent storage.

16. The method of claim 15 further comprising:

allocating a corresponding portion of the SSD for use by each controller of the plurality of storage controllers to cache data associated with a received write request.

17. The method of claim 16 further comprising:

adjusting a size of a portion of the SSD corresponding to a storage controller based on a load associated with the storage controller.

18. The method of claim 15

wherein a plurality of logical volumes are configured on corresponding portions of one or more of the plurality of storage devices,

wherein the method further comprises:

allocating a corresponding portion of the SSD for each of the plurality of logical volumes wherein each storage controller uses the corresponding portion for a logical volume accessed by said each storage controller in processing a received write request to cache data associated with the write request.

19. A method operable in a system, the system comprising a plurality of storage controllers coupled with a plurality of storage devices through a switched fabric communication medium, the switched fabric communication medium comprising two switching devices coupling the each of the plurality of storage controllers with each of the plurality of storage devices, each switching device comprising a solid-state drive (SSD), each switching device further comprising a cluster management controller, the method comprising:

receiving a write request in a storage controller of the plurality of storage controllers, the write request directed to a logical volume configured on portions of one or more of the plurality of storage devices;

caching data associated with the write request from the storage controller into the SSD of one or more of the switching devices;

synchronizing cached data between the two switching devices by operation of the cluster management controller in each of the two switching devices; and

flushing, by operation of the cluster management controller of a switching device, cached data from its SSD to the logical volume for persistent storage.