Storage array snapshots for logged access replication in a continuous data protection system

• US 8,335,771 B1
• Filed: 09/29/2010
• Issued: 12/18/2012
• Est. Priority Date: 09/29/2010
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Natanzon, Assaf, Don, Arieh, Meiri, David
• Primary Examiner(s): Jalil, Neveen Abel
• Assistant Examiner(s): PANDYA, JAGDISH J
• Application Number:
  US12/893,594
• Time in Patent Office: 811 Days
• Field of Search: 707/684, 714/6.3, 711/162
• US Class Current: 707/684
• CPC Class Codes: G06F 11/2069 Management of state, configuration or failover
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 16/2308 Concurrency control transaction processing G06F9/466
• CPC Class Codes: G06F 2201/855 Details of asynchronous mirroring using a journal to transfer not-yet-mirrored changes

Abstract

Methods and apparatus for a continuous data protection system having a protection agent and at least one data protection appliance that enables, in an image access mode, a rolling back of volumes in a highly available storage array on the target side so that the volumes contain data for a selected point in time, creation of a storage array snapshot of the volumes for the point in time, and user access to the storage array snapshot in the storage array.

Claims

1. A method, comprising:

for a continuous data protection system having a protection agent and at least one data protection appliance,

enabling, in an image access mode, a rolling back of volumes in a highly available storage array on the target side so that the volumes contain data for a selected point in time;

enabling creation of a storage array snapshot of the volumes for the point in time;

enabling a user to access the storage array snapshot in the storage array;

performing a production side recovery from the image access mode, comprising;

transitioning source volumes to a target side inactive state;

transitioning target volumes to a source side active state; and

tracking changes in the target side including after synchronization;

starting replication from the target side to the source side;

waiting for data tracked in the protection area to be pushed to the replica site and waiting for volume synchronization;

transitioning the target volumes to a target side inactive state;

rolling the source volumes to a point in time;

creating a storage array snapshot for the source volumes;

transitioning the source volumes to a source side active state;

switching the replication direction back to the target side; and

discarding a journal for the replication system, discarding the virtual snapshot, and starting replication.

2. The method according to claim 1, wherein the data protection appliance forms a part of the storage array and/or a host coupled to the storage array via a switch.

3. The method according to claim 1, further including tracking I/Os in a protection area in the storage array.

4. The method according to claim 1, further including allowing writes to the storage array while the storage array snapshot remains at the point in time.

5. The method according to claim 1, further including discarding the access point comprising promoting the storage array snapshot to the volumes.

6. The method according to claim 5, further including clearing I/Os tracked in a protection area.

7. The method according to claim 1, further including performing a failover from the source side to the target side, comprising:

transitioning the source volumes to a target side inactive state;

transitioning the target volumes to a source side active state;

deleting the virtual snapshot; and

starting replication from the target side to the source side.

8. A method, comprising:

for a continuous data protection system having a protection agent and at least one data protection appliance,

enabling, in an image access mode, a rolling back of volumes in a highly available storage array on the target side so that the volumes contain data for a selected point in time;

enabling creation of a storage array snapshot of the volumes for the point in time;

enabling a user to access the storage array snapshot in the storage array;

performing a production side recovery from the image access mode, comprising;

transitioning source volumes to a target side inactive state;

transiting target volumes to a source side active state; and

tracking changes in the target side including after synchronization;

starting replication from the target side to the source side;

waiting for data tracked in the protection area to be pushed to the replica site and waiting for volume synchronization;

transitioning the target volumes to a target side inactive state;

rolling the source volumes to a point in time;

creating a storage array snapshot for the source volumes;

transitioning the source volumes to a source side active state;

switching the replication direction back to the target side; and

maintaining a journal for the replication system, promoting the virtual snapshot, adding changes to the remote volumes since the point in time to a list of differences, and starting replication.

9. An article, comprising:

computer readable medium containing stored non-transitory instructions that enable a computer to perform the steps of;

for a continuous data protection system having a source side protection agent and a target side protection agent and at least one data protection appliance,

enabling, in an image access mode, a rolling back of volumes in a highly available storage array on a target side so that the volumes contain data for a selected point in time;

enabling creation of a storage array snapshot of the volumes for the point in time;

enabling a user to access the storage array snapshot in the storage array;

performing a production side recovery from the image access mode, comprising;

transitioning source volumes to a target side inactive state;

transitioning target volumes to a source side active state; and

tracking changes in the target side including after synchronization;

starting replication from the target side to the source side;

waiting for data tracked in the protection area to be pushed to the replica site and waiting for volume synchronization;

transitioning the target volumes to a target side inactive state;

rolling the source volumes to a point in time;

creating a storage array snapshot for the source volumes;

transitioning the source volumes to a source side active state;

switching the replication direction back to the target side; and

discarding a journal for the replication system, discarding the virtual snapshot, and starting replication.

10. The article according to claim 9, wherein the data protection appliance forms a part of the storage array and/or a host coupled to the storage array via a switch.

11. The article according to claim 9, further including instructions for tracking I/Os in a protection area in the storage array.

12. The article according to claim 9, further including instructions for allowing writes to the storage array while the storage array snapshot remains at the point in time.

13. A system, comprising:

a processor; and

a memory that stores processor-executable instructions to enable the processor to;

for a continuous data protection system having a source side protection agent and a target side protection agent and at least one data protection appliance,

enable, in an image access mode, a rolling back of volumes in a highly available storage array on a target side so that the volumes contain data for a selected point in time;

enable creation of a storage array snapshot of the volumes for the point in time;

enable a user to access the storage array snapshot in the storage array;

perform a production side recovery from the image access mode, comprising;

transitioning source volumes to a target side inactive state;

transitioning target volumes to a source side active state; and

tracking changes in the target side including after synchronization;

start replication from the target side to the source side;

wait for the data tracked in the protection area to be pushed to the replica site and waiting for volume synchronization;

transition the target volumes to a target side inactive state;

roll the source volumes to a point in time;

create a storage array snapshot for the source volumes;

transition the source volumes to a source side active state;

switch the replication direction back to the target side; and

discard a journal for the replication system, discarding the virtual snapshot, and start replication.