Using persistent memory technology as a host-side storage tier for clustered/distributed file systems, managed by host-side tier

• US 10,452,544 B1
• Filed: 09/27/2017
• Issued: 10/22/2019
• Est. Priority Date: 09/27/2017
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Smaldone, Stephen, Wigmore, Ian, Don, Arieh
• Primary Examiner(s): Rones, Charles
• Assistant Examiner(s): Doan, Han V
• Application Number:
  US15/717,771
• Time in Patent Office: 755 Days
• CPC Class Codes: G06F 12/0811 with multilevel cache hierarchies
• CPC Class Codes: G06F 12/0813 with a network or matrix configuration
• CPC Class Codes: G06F 12/0815 Cache consistency protocols
• CPC Class Codes: G06F 12/0868 Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
• CPC Class Codes: G06F 16/13 File access structures, e.g. distributed indices arrangements of input from, or output to, record carriers G06F3/06
• CPC Class Codes: G06F 16/172 Caching, prefetching or hoarding of files
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: G06F 2212/1041 Resource optimization
• CPC Class Codes: G06F 2212/1056 Simplification
• CPC Class Codes: G06F 2212/154 Networked environment
• CPC Class Codes: G06F 2212/311 In host system
• CPC Class Codes: G06F 2212/312 In storage controller
• CPC Class Codes: G06F 2212/463 File

Abstract

Embodiments are described for a multi-node file system, such as a clustered or distributed file system, with a file system buffer cache and an additional host-side tier non-volatile storage cache such as 3DXP storage. Cache coherency can be maintained by one of three models: (i) host-side tier management, (ii) file system management, or (iii) storage array management. performing a storage tier-specific file system action in a file system that comprises a namespace that spans multiple tiers of storage.

Claims

1. A computer-implemented method for managing cache coherency of a multi-node file system sharing a storage system, each node having a file system buffer cache and a host-side cache, comprising:

receiving, by a host-side cache on a first node of the multi-node file system, a copy of a file system object (FSO) from a file system buffer cache on the first node;

storing the copy of the FSO in the host-side cache on the first node;

sending, by the first node, a message to a second and a third node to invalidate a copy of the FSO in a host-side cache of each of the second and third nodes in response to the storing of the copy of the FSO in the host-side cache on the first node from the buffer cache on the first node; and

sending a copy of the FSO from the host-side cache of the first node to at least the host-side cache of the second node independently of the shared storage system;

wherein each of the first, second, and third nodes comprise host-side cache coherency logic, and the coherency logic of the host-side cache of the first, second, and third nodes communicate with each other to implement coherency logic for the combined first, second, and third node host-side caches.

2. The method of claim 1, wherein the host-side cache comprises a non-volatile storage, distinct from the file system buffer cache.

3. The method of claim 1, wherein cache coherency logic of the host-side cache of the first node is independent of cache coherency logic of the file system buffer cache of the first node.

4. The method of claim 1, wherein the sending of the copy of the FSO from the host-side cache of the first node to the host-side cache of the second node is in response to a request from the second node.

5. The method of claim 1, wherein the copy of the FSO received from the file system buffer cache of the first node was received in response to a read request of an outdated copy of the FSO.

6. The method of claim 1, further comprising flushing the received copy of the FSO from the host-side cache of the first node to the storage system in response to an event, wherein the event comprises one of:

a receipt of a flush host-side cache message,

the FSO has not been read for a predetermined period of time,

storage available in the host-side cache of the first node is below a threshold minimum value, or

receipt of a request to flush pending writes has been received from the storage system.

7. A non-transitory computer-readable medium programmed with executable instructions that, when executed by a processing system having at least one hardware processor, perform operations for managing cache coherency of a multi-node file system sharing a storage system, each node having a file system buffer cache and a host-side cache, comprising:

receiving, by a host-side cache on a first node of the multi-node file system, a copy of a file system object (FSO) from a file system buffer cache on the first node;

storing the copy of the FSO in the host-side cache on the first node;

sending, by the first node, a message to a second and a third node to invalidate a copy of the FSO in a host-side cache of each of the second and third nodes in response to the storing of the copy of the FSO in the host-side cache on the first node from the buffer cache on the first node; and

sending a copy of the FSO from the host-side cache of the first node to at least the host-side cache of the second node independently of the shared storage system;

wherein each of the first, second, and third nodes comprise host-side cache coherency logic, and the coherency logic of the host-side cache of the first, second, and third nodes communicate with each other to implement coherency logic for the combined first, second, and third node host-side caches.

8. The medium of claim 7, wherein the host-side cache comprises a non-volatile storage, distinct from the file system buffer cache.

9. The medium of claim 7, wherein cache coherency logic of the host-side cache of the first node is independent of cache coherency logic of the file system buffer cache of the first node.

10. The medium of claim 7, wherein the sending of the copy of the FSO from the host-side cache of the first node to the host-side cache of the second node is in response to a request from the second node.

11. The medium of claim 7, wherein the copy of FSO received from the file system buffer cache of the first node was received in response to a read request of an outdated copy of the FSO.

12. The medium of claim 7, further comprising flushing the received copy of the FSO from the host-side cache of the first node to the storage system in response to an event, wherein the event comprises one of:

a receipt of a flush host-side cache message,

the FSO has not been read for a predetermined period of time,

storage available in the host-side cache of the first node is below a threshold minimum value, or

receipt of a request to flush pending writes has been received from the storage system.

13. A system comprising:

a processing system having at least one hardware processor, the processing system coupled to a memory programmed with executable instructions that, when executed by the processing system, perform operations for managing cache coherency of a multi-node file system sharing a storage system, each node having a file system buffer cache and a host-side cache, comprising;

receiving, by a host-side cache on a first node of the multi-node file system, a copy of a file system object (FSO) from a file system buffer cache on the first node;

storing the copy of the FSO in the host-side cache on the first node;

sending, by the first node, a message to a second and a third node to invalidate a copy of the FSO in a host-side cache of each of the second and third nodes in response to the storing of the copy of the FSO in the host-side cache on the first node from the buffer cache on the first node; and

sending a copy of the FSO from the host-side cache of the first node to at least the host-side cache of the second node independently of the shared storage system;

wherein each of the first, second, and third nodes comprise host-side cache coherency logic, and the coherency logic of the host-side cache of the first, second, and third nodes communicate with each other to implement coherency logic for the combined first, second, and third node host-side caches.

14. The system of claim 13, wherein the host-side cache comprises a non-volatile storage, distinct from the file system buffer cache.

15. The system of claim 13, wherein cache coherency logic of the host-side cache of the first node is independent of cache coherency logic of the file system buffer cache of the first node.

16. The system of claim 13, wherein the sending of the copy of the FSO from the host-side cache of the first node to the host-side cache of the second node is in response to a request from the second node.

17. The system of claim 13, wherein the copy of the FSO received from the file system buffer cache of the first node was received in response to a read request of an outdated copy of the FSO.

18. The system of claim 13, further comprising flushing the received copy of the FSO from the host-side cache of the first node to the storage system in response to an event, wherein the event comprises one of:

a receipt of a flush host-side cache message,

the FSO has not been read for a predetermined period of time,

storage available in the host-side cache of the first node is below a threshold minimum value, or

receipt of a request to flush pending writes has been received from the storage system.