Replication of a consistency group of data storage objects from servers in a data network

• US 20070136389A1
• Filed: 11/29/2005
• Published: 06/14/2007
• Est. Priority Date: 11/29/2005
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Bergant, Milena, Zheng, Jiannan, Zhu, Daniel, Hayden, John
• Granted Patent: US 7,765,187 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• 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 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

Consistency errors may arise during replication of diverse data storage objects from servers in a data network. For preventing consistency errors, a server is programmed for responding to a request for a report of whether or not the server can replicate the dataset without causing a consistency error. Such a report is useful for replicating a consistency group of objects from more than one server. Preparation for replication can be begun at each of the servers, and if any of the servers fail to report that replication can be done without causing a consistency error, the preparation can be aborted so that write access by applications will not be disrupted while the potential problem is diagnosed and eliminated.

Claims

1. In a data processing network including a server, a computer-implemented method comprising the steps of:

the server receiving a request to determine whether or not the server can replicate a dataset from computer data storage of the server without causing a consistency error, and

the server responding to the request by determining whether or not the server can replicate the dataset from the computer data storage of the server without causing a consistency error, and reporting whether or not the server can replicate the dataset from the computer data storage of the server without causing a consistency error.

2. The computer-implemented method as claimed in claim 1, wherein the data processing network includes a client operated by a system administrator, and the client originates the request to determine whether or not the server can replicate the dataset from the computer data storage of the server without causing a consistency error, and the client receives the report of whether or not the server can replicate the dataset from the computer data storage of the server without causing a consistency error.

3. The computer-implemented method as claimed in claim 1, wherein the server reports that the dataset cannot be replicated from the computer data storage of the server without a consistency error, and wherein the method further includes a system administrator responding to the report by shutting down an application having access to the dataset.

4. The computer-implemented method as claimed in claim 1, which further includes the server receiving a destination validation request to determine whether or not the server can connect to a destination for replicated data from the dataset;

and

the server responding to the destination validation request by determining whether or not the server can connect to the destination for the replicated data from the dataset, and reporting whether or not the server can connect to the destination for the replicated data from the dataset.

5. The computer-implemented method as claimed in claim 1, which further includes the server receiving a destination configuration request to configure a destination for replicated data from the dataset;

and

the server responding to the destination configuration request by attempting to configure the destination for storage of replicated data from the dataset, and reporting whether or not the destination for the replicated data from the dataset has been successfully configured for storage of the replicated data from the dataset.

6. The computer-implemented method as claimed in claim 1, wherein the data processing network includes a plurality of servers providing access of applications to respective datasets, and wherein a controller sends, to each of the servers, a request to determine whether or not each of the servers can replicate the respective dataset without causing a consistency error, and wherein each of the servers returns, to the controller, a report of whether or not said each of the servers can replicate the respective dataset without causing a consistency error.

7. The computer-implemented method as claimed in claim 6, which includes the controller receiving the reports from the servers, and upon checking that all of the servers can replicate their respective datasets without causing consistency errors, the controller sending a replicate request to each of the servers in order to replicate a consistency group of the datasets from the servers.

8. The computer-implemented method as claimed in claim 6, wherein clients in the data processing network use different high-level storage access protocols to access the respective datasets.

9. The computer-implemented method as claimed in claim 1, wherein the server determines whether or not the server can replicate the dataset from the computer data storage of the server without causing a consistency error by suspending write access of applications to the dataset, and then checking whether any applications fail to release any read-write locks upon the dataset.

10. The computer-implemented method as claimed in claim 9, wherein at least one application holds a read-write lock upon the dataset when the server suspends write access of applications to the dataset, and the server requests said at least one application to release the read-write lock upon the dataset.

11. The computer-implemented method as claimed in claim 1, which includes replicating the dataset by activating a snapshot facility in the server to take a snapshot copy of the dataset in the computer data storage of the server, and activating a replication control protocol facility in the server to replicate the dataset over the data processing network from the server using the Transmission Control Protocol.

12. The computer-implemented method as claimed in claim 1, wherein the method includes replicating a first snapshot copy of the dataset over the data processing network from the server and then replicating, over the data processing network from the server, changes made to the dataset from the time of the first snapshot copy of the dataset up to a time of making a second snapshot copy of the dataset.

13. The computer-implemented method as claimed in claim 1, wherein the dataset includes a logical unit number (LUN) of storage, and the method includes encapsulating the logical unit number (LUN) of storage in a file and replicating the file over the data processing network from the server.

14. A computer-implemented method of replicating data storage objects over a data network from respective servers, said method comprising:

(a) the servers modifying the data storage objects in computer data storage of the servers by executing transactions of applications upon the data storage objects, at least one of the applications accessing at least some of the data storage objects in the computer data storage of more than one of the servers;

(b) temporarily suspending write access of the applications at the servers to the data storage objects upon completion of pending ones of the transactions of the applications;

(c) replicating the data storage objects to produce a replica of a consistency group for transmission of the replica of the consistency group over the data network from the servers; and

(d) resuming write access of each of the applications to the data storage objects, and transmitting the replica of the consistency group over the data network from the servers.

15. The computer-implemented method as claimed in claim 14, which includes using at least one snapshot facility for replicating the data storage objects to produce the replica of the consistency group for transmission of the replica of the consistency group over the data network from the servers.

16. The computer-implemented method as claimed in claim 14, which further includes:

(e) keeping a record of changes to the data storage objects since producing the replica of the consistency group in step (c);

(f) again temporarily suspending write access of the applications at the servers to the data storage objects upon completion of pending ones of the transactions of the applications; and

(g) replicating changes made to the data storage objects since producing the replica of the consistency group in step (c) up to the temporary suspension of write access in step (f) in order to produce a replica of a differential consistency group, and transmitting the replica of the differential consistency group over the data network from the servers.

17. The computer-implemented method as claimed in claim 14, which includes network clients using different high-level access protocols to access the data storage objects in the servers.

18. The computer-implemented method as claimed in claim 14, which includes encapsulating a logical unit number (LUN) of storage into a file and including the file in the consistency group.

19. The computer-implemented method as claimed in claim 14, which includes each of the servers replicating the data storage objects accessed by said each of the servers to produce a replica of a consistency group for transmission of the replica of the consistency group from the servers over the data network upon receiving confirmation that the other servers can be successful in temporarily suspending write access to the data storage objects accessed by the other servers.

20. The computer-implemented method as claimed in claim 14, which further includes:

a controller requesting each of the servers to temporarily suspend write access to the data storage objects upon completion of pending ones of the transactions of the applications;

each of the servers replying to the controller that write access to the data storage objects can be successfully suspended upon completion of the pending ones of the transactions of the applications; and

then

once the controller has received the replies from all of the servers indicating that all write access to the data storage objects can be successfully suspended upon completion of the pending ones of the transactions of the applications, the controller requesting the servers to replicate the data storage objects to produce the replica of the consistency group for transmission of the replica of the consistency group over the data network from the servers.