Method and system for performing replication to a device while allowing application access

Patent metadata

Field	Value
Publication number	US-9934302-B1
Application number	US-201414502250-A
Country	US
Kind code	B1
Filing date	Sep 30, 2014
Priority date	Sep 30, 2014
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

Example embodiments of the present invention relate to a method, a system, and a computer program product for enabling concurrent host access at a replica site to a point in time different than a current point in time of a replication environment. The method includes performing data protection from a production site to a replica site in a replication environment and enabling concurrent host access at the replica site to a point in time different than a current point in time of the replication environment.

First claim

What is claimed is:

1. A method comprising:
performing data protection from a production site to a replica site in a replication environment;
enabling concurrent host access to a volume data node at the replica site to a point in time different than a current point in time of the replication environment;
enabling the replica site to replicate changes received from the production site, wherein enabling the replica site to replicate changes received from the production site comprises enabling data protection to be performed to a child snapshot node of a parent node of the volume data node, further wherein a replica volume at the replica site is represented as a tree of nodes;
wherein the volume data node is assigned a SCSI personality identifying the volume data node as an access target for access by a replica site host; and
wherein the child snapshot node of the parent node of the volume data node is assigned a snapshot SCSI personality identifying the snapshot node as a replication target for replication of I/Os from the production site;

performing failover to the replica volume comprising:
determining differences between the replica site and the production site;
sending the differences to the production site for replication to a production volume; and
performing data protection from the replica site to the production site;
wherein determining differences between the replica site and the production site comprises:
determining a first set of differences at the replica site resulting from data protection being performed to the snapshot node;
determining a second set of differences at the replica site resulting from host access to the volume data node;
merging the first set of differences and the second set of differences;
sending the merged differences to the production site for replication to a production volume; and

wherein the snapshot node is a first snapshot node;
wherein the volume data node is a first volume data node;
wherein determining a first set of differences at the replica site resulting from data protection being performed to the snapshot node comprises:
creating a second snapshot node as a child node of the first snapshot node;
reassigning the snapshot SCSI personality to the second snapshot node; and
determining the first set of differences between the second snapshot node and a parent node of the first volume data node; and

wherein determining a second set of differences at the replica site resulting from host access to the volume data node comprises:
creating a third snapshot node as a child node of the first volume data node;
creating a second volume data node as a child node of the first volume data node;
reassigning the SCSI personality to the second volume data node; and
determining the second set of differences between the third snapshot node and the parent node of the first volume data node.

2. The method of claim 1
wherein enabling host access to the volume data node comprises:
receiving a selection of a snapshot at the replica site for image access represented as a snapshot node in the tree of nodes representing the replica volume;
creating the volume data node as a child node of the snapshot node; and
reassigning the SCSI personality to the created volume data node identifying the created volume data node as the access target for access by a replica site host; and

wherein enabling data protection to be performed to a child snapshot node of a parent node of the volume data node comprises enabling data protection to continue to the snapshot node concurrent with host access to the volume data node.

3. The method of claim 2 wherein the snapshot node is a first snapshot node, the method further comprising:
creating a second snapshot node as a child node of the first snapshot node;
reassigning the snapshot SCSI personality to the second snapshot node; and
enabling data protection to the second snapshot node concurrent with host access to the volume data node.

4. The method of claim 1 further comprising:
removing the first snapshot node and its child nodes from the tree; and
reassigning the snapshot SCSI personality to the third snapshot node.

5. A system comprising:
a replication environment comprising a production site and a replica site further comprising a replication appliance and a host; and
computer program code configured to perform the operations of:
performing data protection from the production site to the replica site in the replication environment;
enabling concurrent host access to a volume data at the replica site to a point in time different than a current point in time of the replication environment;

enabling the replica site to replicate changes received from the production site, wherein enabling the replica site to replicate changes received from the production site comprises enabling data protection to be performed to a child snapshot node of a parent node of the volume data node, further wherein a replica volume at the replica site is represented as a tree of nodes;
wherein the volume data node is assigned a SCSI personality identifying the volume data node as an access target for access by a replica site host; and
wherein the child snapshot node of the parent node of the volume data node is assigned a snapshot SCSI personality identifying the snapshot node as a replication target for replication of I/Os from the production site,

performing failover to the replica volume comprising:
determining differences between the replica site and the production site;
sending the differences to the production site for replication to a production volume; and
performing data production from the replica site to the production site;
wherein determining differences between the replica site and the production site comprises:
determining a first set of differences at the replica site resulting from data protection being performed to the snapshot node;
determining a second set of differences at the replica site resulting from the host access to the volume data node;
merging the first set of differences and the second set of differences;

sending the merged differences to the production site for replication to a production volume; and
wherein the snapshot node is a first snapshot node;
wherein the volume data node is a first volume data node,
wherein determining a first set of differences at the replica site resulting from data protection being performed to the snapshot node comprises:
creating a second snapshot node as a child node of the first snapshot node;
reassigning the snapshot SCSI personality to the second snapshot node; and
determining the first set of differences between the second snapshot node and a parent node of the first volume data node; and
wherein determining a second set of differences at the replica site resulting from host access to the volume data node comprises:
creating a third snapshot node as a child node of the first volume data node;
creating a second volume data node as a child node of the first volume data node;
reassigning the SCSI personality to the second volume data node; and
determining the second set of differences between the third snapshot node and the parent node of the first volume data node.

6. The system of claim 5
wherein enabling host access to the volume data node comprises:
receiving a selection of a snapshot at the replica site for image access represented as a snapshot node in the tree of nodes representing the replica volume;
creating the volume data node as a child node of the snapshot node; and
reassigning the SCSI personality to the created volume data node identifying the created volume data node as the access target for access by a replica site host; and

wherein enabling data protection to be performed to a chi

Assignees

• Emc Corp
• Emc Ip Holding Co Llc

Inventors

• Cohen Saar
• Natanzon Assaf
• Lotosh Valerie
• Zendel Roman
• Halevi Ido

Classifications

• G06F16/273 Primary

  Asynchronous replication or reconciliation · CPC title

• G06F17/30575 Primary

  Physics · mapped topic

• G06F17/30578

  Physics · mapped topic