Entity management in distributed systems

• US 10,362,092 B1
• Filed: 10/14/2016
• Issued: 07/23/2019
• Est. Priority Date: 10/14/2016
• Status: Active Grant

• Current Assignee: Nutanix Incorporated
• Original Assignee: Nutanix Incorporated
• Inventors: Parthasarathy, Ranjan
• Primary Examiner(s): Meky, Moustafa M
• Assistant Examiner(s): Islam, Sm Z
• Application Number:
  US15/294,422
• Time in Patent Office: 1,012 Days
• CPC Class Codes: G06F 3/06 Digital input from, or digital output to, record carriers , e.g. RAID, emulated record carriers or networked record carriers
• 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 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• 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]
• CPC Class Codes: H04L 67/56 Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54

Abstract

Systems for managing shared entities between computing clusters while avoiding race conditions. Multiple clusters are interconnected over a network. When a node of a cluster intends to move a shared data item or virtual machine from its cluster to another cluster, the movement or migration can be initiated by establishing sole ownership followed by a request to an arbiter to intermediate during the movement or migration. The request explicitly includes subject entity metadata that describes sharing states pertaining to the subject entity. Upon granting a request, the arbiter generates a master copy of the entity metadata and grants itself read-write access. Any other sharers of the subject entity observe read-only access while the arbiter maintains the sole master copy. A sharer of the subject entity can cause changes to the subject entity through the arbiter. The arbiter can pass ownership to a new cluster to complete the subject entity migration.

Claims

1. A method, comprising:

forming, by a node in a first cluster, a migration request to migrate subject entity metadata;

receiving, by a second cluster, the migration request to migrate the subject entity metadata to a cluster other than the first cluster;

generating parent entity metadata, the parent entity metadata being a current representation of the subject entity metadata that is delivered to a central access point within the second cluster, wherein read-write access by the central access point is granted by receipt of the migration request;

modifying, by the first cluster, at least a portion of the subject entity metadata to cause the subject entity metadata to be read-only accessible by the first cluster;

receiving, by the second cluster, a request to modify the parent entity metadata;

modifying the parent entity metadata to produce updated parent entity metadata; and

sending, by the second cluster, at least a portion of the updated parent entity metadata.

2. The method of claim 1, further comprising modifying at least a portion of the subject entity metadata to cause the subject entity metadata to be read-write accessible by a local access point.

3. The method of claim 1, wherein generating the parent entity metadata is responsive to registering the first cluster or the second cluster with the central access point.

4. The method of claim 1, wherein the subject entity metadata is distributed across two or more clusters.

5. The method of claim 1, wherein the central access point is selected from any node of the second cluster.

6. The method of claim 1, wherein modifying the portion of the subject entity metadata comprises performing at least one atomic operation.

7. The method of claim 1, wherein modifying the portion of the subject entity metadata comprises is a compare-and-swap operation.

8. The method of claim 1, wherein modifying the portion of the subject entity metadata comprises adding a parent field to the subject entity metadata, and populating the parent field.

9. The method of claim 1, wherein modifying the portion of the subject entity metadata comprises adding a parent field to the subject entity metadata, and populating the parent field is populated with a parent entity metadata identifier.

10. The method of claim 1, wherein the request is invoked by at least one of, a cluster expansion, or a cluster migration.

11. A non-transitory computer readable medium having stored thereon a sequence of instructions which, when executed by a processor performs a set of acts, comprising:

forming, by a node in a first cluster, a migration request to migrate subject entity metadata;

receiving, by a second cluster, the migration request to migrate the subject entity metadata to a cluster other than the first cluster;

generating parent entity metadata, the parent entity metadata being a current representation of the subject entity metadata that is delivered to a central access point within the second cluster, wherein read-write access by the central access point is granted by receipt of the migration request;

modifying, by the first cluster, at least a portion of the subject entity metadata to cause the subject entity metadata to be read-only accessible by the first cluster;

receiving, by the second cluster, a request to modify the parent entity metadata;

modifying the parent entity metadata to produce updated parent entity metadata; and

sending, by the second cluster, at least a portion of the updated parent entity metadata.

12. The computer readable medium of claim 11, wherein the set of acts further comprise modifying at least a portion of the subject entity metadata to cause the subject entity metadata to be read-write accessible by a local access point.

13. The computer readable medium of claim 11, wherein generating the parent entity metadata is responsive to registering the first cluster or the second cluster with the central access point.

14. The computer readable medium of claim 11, wherein the subject entity metadata is distributed across two or more clusters.

15. The computer readable medium of claim 11, wherein the central access point is selected from any node of the second cluster.

16. The computer readable medium of claim 11, wherein modifying the portion of the subject entity metadata comprises performing at least one atomic operation.

17. The computer readable medium of claim 11, wherein modifying the portion of the subject entity metadata comprises is a compare-and-swap operation.

18. The computer readable medium of claim 11, wherein modifying the portion of the subject entity metadata comprises adding a parent field to the subject entity metadata, and populating the parent field.

19. A system, comprising:

a storage medium having stored thereon a sequence of instructions; and

a processor executes the sequence of instructions to to perform a set of acts, comprising,

forming, by a node in a first cluster, a migration request to migrate subject entity metadata;

receiving, by a second cluster, the migration request to migrate the subject entity metadata to a cluster other than the first cluster;

generating parent entity metadata, the parent entity metadata being a current representation of the subject entity metadata that is delivered to a central access point within the second cluster, wherein read-write access by the central access point is granted by receipt of the migration request;

modifying, by the first cluster, at least a portion of the subject entity metadata to cause the subject entity metadata to be read-only accessible by the first cluster;

receiving, by the second cluster, a request to modify the parent entity metadata;

modifying the parent entity metadata to produce updated parent entity metadata; and

sending, by the second cluster, at least a portion of the updated parent entity metadata.

20. The system of claim 19, further comprising modifying at least a portion of the subject entity metadata to cause the subject entity metadata to be read-write accessible by a local access point.

21. A method, comprising:

forming, by a node in a first cluster, a request to relocate subject entity metadata;

receiving, by a second cluster, the request to relocate the subject entity metadata to a cluster other than the first cluster;

generating parent entity metadata, the parent entity metadata being a current representation of the subject entity metadata that is delivered to a central access point within the second cluster, wherein read-write access by the central access point is granted by receipt of the request;

modifying, by the first cluster, at least a portion of the subject entity metadata to cause the subject entity metadata to be read-only accessible by the first cluster;

receiving, by the second cluster, a request to modify the parent entity metadata;

modifying the parent entity metadata to produce updated parent entity metadata; and

sending, by the second cluster, at least a portion of the updated parent entity metadata.

22. The method of claim 21, further comprising modifying at least a portion of the subject entity metadata to cause the subject entity metadata to be read-write accessible by a local access point.

23. The method of claim 21, wherein generating the parent entity metadata is responsive to registering the first cluster or the second cluster with the central access point.

24. The method of claim 21, wherein the subject entity metadata is distributed across two or more clusters.

25. The method of claim 21, wherein the central access point is selected from any node of the second cluster.