Preserving replication to a storage object on a storage node

Patent metadata

Field	Value
Publication number	US-10747465-B2
Application number	US-201816175162-A
Country	US
Kind code	B2
Filing date	Oct 30, 2018
Priority date	Oct 30, 2018
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

A technique preserves replication to a storage node. The technique involves, from a first storage node, sending a replication query to a second storage node. The technique further involves, in response to the replication query sent to the second storage node, receiving replication session data from the second storage node. The replication session data describes replication which has terminated from a third storage node to the second storage node for a particular storage object. The technique further involves, based on the replication session data, establishing replication from the first storage node to the second storage node for the particular storage object to preserve use of the particular storage object.

First claim

What is claimed is:

1. A method of preserving replication to a storage node, the method comprising:
from a first storage node, sending a replication query to a second storage node;
in response to the replication query sent to the second storage node, receiving replication session data from the second storage node, the replication session data describing replication which has terminated between a third storage node and the second storage node for a particular storage object; and
based on the replication session data, establishing replication from the first storage node to the second storage node for the particular storage object to preserve use of the particular storage object;
wherein, prior to establishing replication from the first storage node to the second storage node, (i) a current version of the particular storage object resides on the first storage node and (ii) a non-current version of the particular storage object resides on the second storage node; and
wherein establishing replication from the first storage node to the second storage node for the particular storage object includes:
updating the non-current version of the particular storage object residing on the second storage node to match the current version of the particular storage object residing on the first storage node.

2. A method as in claim 1 wherein updating the non-current version of the particular storage object residing on the second storage node to match the current version of the particular storage object residing on the first storage node includes:
identifying a set of changes between the non-current version of the particular storage object residing on the second storage node and the current version of the particular storage object residing on the first storage node, and
sending only the set of changes from the first storage node to the second storage node to update the non-current version of the particular storage object residing on the second storage node in lieu of sending an entire copy of the current version of the particular storage object from the first storage node to the second storage node.

3. A method as in claim 2 wherein the current version of the particular storage object is formed from synchronous replication from the third storage node to the first storage node prior to a failover event;
wherein the non-current version of the particular storage object stored by the second storage node is formed by asynchronous replication from the third storage node to the second storage node prior to the failover event; and
wherein establishing replication from the first storage node to the second storage node further includes:
after the set of changes is sent from the first storage node to the second storage node to update the non-current version of the particular storage object, performing asynchronous replication from the first storage node to the second storage node for the particular storage object.

4. A method as in claim 1 wherein, prior to sending the replication query, asynchronous replication is performed from the third storage node to the second storage node for the particular storage object; and
wherein sending the replication query to the second storage node includes:
providing the replication query to the second storage node after the asynchronous replication from the third storage node to the second storage node for the particular storage object has been terminated.

5. A method as in claim 4 wherein the asynchronous replication from the third storage node to the second storage node for the particular storage object is performed via an asynchronous replication session between the third storage node and the second storage node having (i) a replication session identifier that uniquely identifies the asynchronous replication session among other replication sessions and (ii) a recovery point objective (RPO) that identifies a target period in which data for the particular storage object might be lost due to an incident; and
wherein receiving the replication session data from the second storage node includes:
acquiring, as at least a portion of the replication session data, the replication session identifier and the RPO from the second storage node.

6. A method as in claim 5 wherein establishing replication from the first storage node to the second storage node for the particular storage object further includes:
establishing an asynchronous replication session between the first storage node and the second storage node based on the replication session identifier and the RPO from the second storage node.

7. A method as in claim 1 , further comprising:
while establishing replication from the first storage node to the second storage node for the particular storage object, concurrently establishing replication from the first storage node to the third storage node for the particular storage object.

8. A method as in claim 7 wherein establishing replication from the first storage node to the second storage node for the particular storage object further includes:
establishing an asynchronous replication session between the first storage node and the second storage node for the particular storage object, and
activating the asynchronous replication session to perform asynchronous replication from the first storage node to the second storage node for the particular storage object; and
wherein concurrently establishing replication from the first storage node to the third storage node for the particular storage object includes:
establishing a synchronous replication session between the first storage node and the third storage node for the particular storage object, and
activating the synchronous replication session to perform synchronous replication from the first storage node to the third storage node for the particular storage object.

9. A method as in claim 8 wherein activating the asynchronous replication session includes transitioning the asynchronous replication session to an active state; and
wherein the method further comprises:
after the asynchronous replication session has been in the active state for a period of time, transitioning the asynchronous replication session from the active state to a hibernated state to deactivate replication from the first storage node to the second storage node for the particular storage object and enable the third storage node to perform replication to the second storage node for the particular storage object.

10. A method as in claim 1 , further comprising:
prior to sending the replication query to the second storage node, performing replication to the second storage node for the particular storage object, and
terminating replication to the second storage node for the particular storage object.

11. A method as in claim 10 wherein performing replication to the second storage node for the particular storage object includes:
establishing an asynchronous replication session between the first storage node and the second storage node for the particular storage object, and
activating the asynchronous replication session to perform asynchronous, replication from the first storage node to the second storage node for the particular storage object; and
wherein terminating replication to the second storage node for the particular storage object includes:
deactivating the asynchronous replication session in response to a failover event.

12. A method as in claim 11 wherein activating the asynchronous replication session includes transitioning the asynchronous replication session to an active state;
wherein deactivating the asynchronous replication session includes transitioning the asynchronous replication session from

Assignees

• Emc Ip Holding Co Llc

Inventors

• Shang Qiu
• Subramanian Vasu
• Qu Qi
• Xiong Tianfang
• Qian Yue

Classifications

• G06F3/0617

  in relation to availability · CPC title

• G06F3/065 Primary

  Replication mechanisms · CPC title

• G06F3/0619

  in relation to data integrity, e.g. data losses, bit errors · CPC title

• G06F3/067

  Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS] · CPC title

• G06F11/2064

  while ensuring consistency · CPC title