Method to discover multiple paths to disk devices cluster wide

• US 9,015,371 B1
• Filed: 03/01/2012
• Issued: 04/21/2015
• Est. Priority Date: 03/01/2012
• Status: Active Grant

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Randhawa, Amarinder Singh, Nayak, Sathish, Dash, Prasanta Ranjan
• Primary Examiner(s): RHU, KRIS M
• Application Number:
  US13/410,044
• Time in Patent Office: 1,146 Days
• Field of Search: None
• US Class Current: 710/38
• CPC Class Codes: G06F 13/4063 Device-to-bus coupling
• CPC Class Codes: H04L 45/24 Multipath
• CPC Class Codes: H04L 45/46 Cluster building
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

A system and method for discovering multiple paths to a disk device are disclosed. For example, the method can include discovering a plurality of paths that exist from a first host computer to a storage device. The plurality of paths includes at least one local path and at least one network path from the first host computer to the storage device. In addition, the first host computer is one of several host computers in a cluster. Once the paths have been discovered, a representation of the paths from the first host computer to the storage device is generated. Such a method can be performed, for example, without user intervention.

Claims

1. A method comprising:

discovering a plurality of paths from a first host computer to a storage device,

wherein

the plurality of paths comprise at least one local path from the first host computer to the storage device,

the plurality of paths comprise at least one network path from the first host computer to the storage device, and

the first host computer is one a plurality of host computers in a cluster;

generating a representation of the plurality of paths from the first host computer to the storage device, wherein

the discovering and the generating are performed by the first host computer,

the generating is performed by the first host computer upon joining the cluster, and

the representation comprises information regarding a connectivity status for each of the plurality of paths; and

after the generating, updating at least a portion of the information in the representation, based on one or more changes to the connectivity status for at least one of the plurality of paths, wherein the updating is performed by the first host computer.

2. The method of claim 1, wherein

the representation is a data structure,

the data structure represents the plurality of host computers in the cluster,

the data structure further indicates which of the plurality of host computers in the cluster are connected to the first host computer via a path, and

the data structure further indicates which of the plurality of host computers in the cluster have access to the storage device.

3. The method of claim 2, wherein the data structure is a bitmap.

4. The method of claim 1, further comprising:

receiving event change information, wherein

the event change information comprises information regarding the one or more changes to the connectivity status for the at least one of the plurality of paths; and

processing the event change information to

identify the storage device,

identify a host computer, and

identify a type of event change that has occurred.

5. The method of claim 4, wherein the event change information is received from a disk connectivity module.

6. The method of claim 4, wherein the type of event change indicates that:

a new path has been established,

a previously existing path has been severed,

a previously existing path is now accessible,

a previously existing path is now inaccessible, or

a change in an attribute of a path has been made.

7. The method of claim 4, wherein

the at least the portion of the information in the representation is updated to represent the event change information.

8. The method of claim 7, wherein the processing and the updating are performed automatically upon the receiving the event change information.

9. The method of claim 7, further comprising:

selecting one of the plurality of paths from the first host computer to the storage device on which to distribute an I/O request, wherein

the selecting is performed using the at least the portion of the information in the Representation that has been updated.

10. A non-transitory computer readable storage medium comprising program instructions executable to:

discover a plurality of paths from a first host computer to a storage device,

wherein

the plurality of paths comprise at least one local path from the first host computer to the storage device,

the plurality of paths comprise at least one network path from the first host computer to the storage device, and

the first host computer is one a plurality of host computers in a cluster;

generate a representation of the plurality of paths from the first host computer to the storage device, wherein

the discover and the generate are performed by the first host computer,

the representation is generated by the first host computer upon joining the cluster, and

the representation comprises information regarding a connectivity status for each of the plurality of paths; and

update at least a portion of the information in the representation, based on one or more changes to the connectivity status for at least one of the plurality of paths, after the representation is generated, wherein the update is performed by the first host computer.

11. The non-transitory computer readable storage medium of claim 10, wherein

the representation is a data structure,

the data structure represents the plurality of host computers in the cluster,

the data structure further indicates which of the plurality of host computers in the cluster are connected to the first host computer via a path, and

the data structure further indicates which of the plurality of host computers in the cluster have access to the storage device.

12. The non-transitory computer readable storage medium of claim 10, wherein the program instructions are further executable to:

receive event change information, wherein

the event change information comprises information regarding the one or more changes to the connectivity status for the at least one of the plurality of paths; and

process the event change information to

identify the storage device,

identify a host computer, and

identify a type of event change that has occurred.

13. The non-transitory computer readable storage medium of claim 12, wherein the type of event change indicates that:

a new path has been established,

a previously existing path has been severed,

a previously existing path is now accessible,

a previously existing path is now inaccessible, or

a change in an attribute of a path has been made.

14. The non-transitory computer readable storage medium of claim 12, wherein

the at least a portion of the information in the representation is updated to represent the event change information.

15. The non-transitory computer readable storage medium of claim 14, wherein the program instructions executable to process and update are performed automatically upon receiving the event change information.

16. A system comprising:

one or more processors; and

memory coupled to the one or more processors, wherein the memory stores program instructions executable by the one or more processors to;

discover a plurality of paths from a first host computer to a storage device,

wherein

the plurality of paths comprise at least one local path from the first host computer to the storage device,

the plurality of paths comprise at least one network path from the first host computer to the storage device, and

the first host computer is one a plurality of host computers in a cluster,

generate a representation of the plurality of paths from the first host computer to the storage device, wherein

the discover and the generate are performed by the first host computer,

the representation is generated by the first host computer upon joining the cluster, and

the representation comprises information regarding a connectivity status for each of the plurality of paths, and

update at least a portion of the information in the representation, based on one or more changes to the connectivity status for at least one of the plurality of paths, after the representation is generated, wherein

the update is performed by the first host computer.

17. The system of claim 16, wherein

the representation is a data structure,

the data structure represents the plurality of host computers in the cluster,

the data structure further indicates which of the plurality of host computers in the cluster are connected to the first host computer via a path, and

the data structure further indicates which of the plurality of host computers in the cluster have access to the storage device.

18. The system of claim 16, wherein the program instructions are further executable to:

receive event change information, wherein

the event change information comprises information regarding the one or more changes to the connectivity status for the at least one of the plurality of paths, and

process the event change information to

identify the storage device,

identify a host computer, and

identify a type of event change that has occurred.

19. The system of claim 18, wherein the type of event change indicates that:

a new path has been established,

a previously existing path has been severed,

a previously existing path is now accessible,

a previously existing path is now inaccessible, or

a change in an attribute of a path has been made.

20. The system of claim 18, wherein the program instructions executable to process and update are performed automatically upon receiving the event change information.