METHOD, ELECTRONIC DEVICE AND COMPUTER PROGRAM PRODUCT FOR SNAPSHOT REPLICATION

• US 20200133919A1
• Filed: 10/16/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Ren, Changsheng, Shang, Qiu, Qian, Yue
• Granted Patent: US 11,409,700 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 11/1453 using de-duplication of the data
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/3034 where the computing system component is a storage system, e.g. DASD based or network based digital input from or digital output to record carriers G06F3/06; digital recording or reproducing G11B20/18; 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], H04L67/1097
• CPC Class Codes: G06F 16/11 File system administration, e.g. details of archiving or snapshots file system backup G06F11/14
• CPC Class Codes: G06F 16/128 Details of file system snapshots on the file-level, e.g. snapshot creation, administration, deletion use of snapshots for error detection or correction G06F11/14, G06F11/16
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0641 De-duplication techniques
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

Techniques involve: in response to a first session for asynchronous snapshot replication being established between a first source device and a destination device, determining whether the first source device and the destination device have a common baseline snapshot. Such techniques further involve: in response to determining absence of the baseline snapshot, determining whether initial synchronization from a second source device to the destination device is completed. Such techniques further involve: replicating, based on a result of the determining, at least one user snapshot at the first source device to the destination device. Accordingly, duplicated user snapshots at the destination device are significantly reduced. The snapshot management and space utilization of the destination device are also improved.

Claims

1. A method of snapshot replication, comprising:

in response to a first session for asynchronous snapshot replication being established between a first source device and a destination device, determining whether the first source device and the destination device have a common baseline snapshot, the baseline snapshot indicating progress of snapshot replication;

in response to determining absence of the baseline snapshot, determining whether initial synchronization from a second source device to the destination device is completed, a second session for synchronous snapshot replication existing between the first source device and the second source device before the first session is established, and a previously established third session for asynchronous snapshot replication existing between the second source device and the destination device, the initial synchronization being a part of the third session; and

replicating, based on a result of the determining, at least one user snapshot at the first source device to the destination device.

2. The method of claim 1, wherein replicating the at least one user snapshot to the destination device comprises:

in response to determining that the initial synchronization has been completed, replicating to the destination device a first user snapshot which is created at the first source device after establishment of the first session; and

in response to determining that the initial synchronization has not yet been completed, replicating to the destination device a second user snapshot existing at the first source device.

3. The method of claim 2, wherein the second user snapshot is replicated from the second source device to the first source device during the second session, and wherein replicating to the destination device the second user snapshot comprises:

obtaining a replicate state of the second user snapshot, the replicate state being determined during the second session; and

in response to the replicate state indicating that the second user snapshot has not yet been replicated to the destination device, replicating the second user snapshot to the destination device.

4. The method of claim 1, further comprising:

in response to determining presence of the baseline snapshot, obtaining a replicate state of a third user snapshot which is replicated from the second source device to the first source device after the latest update of the baseline snapshot, the replicate state being determined during the second session; and

in response to the replicate state indicating that the third user snapshot has not yet been replicated to the destination device, replicating the third user snapshot to the destination device.

5. The method of claim 1, wherein determining whether the initial synchronization is completed comprises:

sending a request to the destination device, so that the destination device determines whether the initial synchronization is completed, based on a snapshot identification stored at the destination device; and

in response to receiving from the destination device a positive response to the request, determining that the initial synchronization has been completed.

6. The method of claim 1, wherein determining whether the initial synchronization is completed comprises:

receiving from the destination device a snapshot identification stored at the destination device;

determining whether the snapshot identification is same as a predetermined identification; and

in response to the snapshot identification being different from the predetermined identification, determining that the initial synchronization has been completed.

7. An electronic device, comprising:

a processor; and

a memory coupled with the processor, the memory having instructions stored therein which, when executed by the processor, causing the electronic device to perform acts comprising;

in response to a first session for asynchronous snapshot replication being established between a first source device and a destination device, determining whether the first source device and the destination device have a common baseline snapshot, the baseline snapshot indicating progress of snapshot replication;

in response to determining absence of the baseline snapshot, determining whether initial synchronization from a second source device to the destination device is completed, a second session for synchronous snapshot replication existing between the first source device and the second source device before the first session is established, and a previously established third session for asynchronous snapshot replication existing between the second source device and the destination device, the initial synchronization being a part of the third session; and

replicating, based on a result of the determining, at least one user snapshot at the first source device to the destination device.

8. The electronic device of claim 7, wherein replicating the at least one user snapshot to the destination device comprises:

in response to determining that the initial synchronization has been completed replicating to the destination device a first user snapshot which is created at the first source device after establishment of the first session; and

in response to determining that the initial synchronization has not yet been completed, replicating to the destination device a second user snapshot existing at the first source device.

9. The electronic device of claim 8, wherein the second user snapshot is replicated from the second source device to the first source device during the second session, and wherein replicating to the destination device the second user snapshot comprises:

obtaining a replicate state of the second user snapshot, the replicate state being determined during the second session; and

in response to the replicate state indicating that the second user snapshot has not yet been replicated to the destination device, replicating the second user snapshot to the destination device.

10. The electronic device of claim 7, wherein the acts further comprise:

in response to determining presence of the baseline snapshot, obtaining a replicate state of a third user snapshot which is replicated from the second source device to the first source device after the latest update of the baseline snapshot, the replicate state being determined during the second session; and

in response to the replicate state indicating that the third user snapshot has not yet been replicated to the destination device, replicating the third user snapshot to the destination device.

11. The electronic device of claim 7, wherein determining whether the initial synchronization is completed comprises:

sending a request to the destination device, so that the destination device determines whether the initial synchronization is completed, based on a snapshot identification stored at the destination device; and

in response to receiving from the destination device a positive response to the request, determining that the initial synchronization has been completed.

12. The electronic device of claim 7, wherein determining whether the initial synchronization is completed comprises:

receiving from the destination device a snapshot identification stored at the destination device;

determining whether the snapshot identification is same as a predetermined identification; and

in response to the snapshot identification being different from the predetermined identification, determining that the initial synchronization has been completed.

13. A computer program product having a non-transitory computer readable medium which stores a set of instructions to perform snapshot replication;

the set of instructions, when carried out by computerized circuitry, causing the computerized circuitry to perform a method of;

in response to a first session for asynchronous snapshot replication being established between a first source device and a destination device, determining whether the first source device and the destination device have a common baseline snapshot, the baseline snapshot indicating progress of snapshot replication;

in response to determining absence of the baseline snapshot, determining whether initial synchronization from a second source device to the destination device is completed, a second session for synchronous snapshot replication existing between the first source device and the second source device before the first session is established, and a previously established third session for asynchronous snapshot replication existing between the second source device and the destination device, the initial synchronization being a part of the third session; and

replicating, based on a result of the determining, at least one user snapshot at the first source device to the destination device.