Cluster database with remote data mirroring

• US 6,859,811 B1
• Filed: 01/15/2004
• Issued: 02/22/2005
• Est. Priority Date: 01/15/2004
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Chandrasekaran, Sashikanth, Kehoe, William F.
• Primary Examiner(s): Mizrahi, Diane D.
• Application Number:
  US10/760,013
• Time in Patent Office: 404 Days
• Field of Search: 707/200, 707/201, 707/202, 707/203, 707/204, 707/205, 707/10, 707/102, 709/217, 709/219, 711/147, 711/162, 714/4, 714/147
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1425 by reconfiguration of node membership
• 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 11/2069 Management of state, configuration or failover
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2079 Bidirectional techniques
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence

Abstract

A method and apparatus for mirroring data between a plurality of sites is provided. A replication relationship is established between the plurality of sites that include a first site and a second site. A first database server at the first site receives an indication that a write operation could not be successfully mirrored at the second site. In response to the indication, the first database server initiates a membership voting operation by communicating with a quorum device to determine whether the first database server or a second database server associated with the second site should be removed from the replication membership. If it is determined that the second database server associated with the second site should be removed from the replication membership, then the first database server sends a message to indicate that write operations are no longer to be replicated at the second site.

Claims

1. A method for mirroring data between a plurality of sites, comprising:

establishing a replication relationship between the plurality of sites including a first site and a second site;

replicating at least some changes made at any site of said plurality of sites at each other site of said plurality of sites;

a first server associated with the first site requesting performance of a write operation;

in response to said request, performing the write operation at the first site, and sending a message to request that the write operation be mirrored at the second site;

the first server receiving an indication that the write operation could not be successfully performed at the second site;

in response to the indication, the first server initiating a membership voting operation to determine which of the first server and a second server associated with the second site should be removed from said replication membership; and

if it is determined that the second server associated with the second site should be removed from said replication membership, then the first server sending a message to indicate that write operations are no longer to be replicated at said second site.

2. The method of claim 1, further comprising the steps of:

the second site rejoining the replication relationship; and

in response to said second site rejoining the replication relationship, causing data associated with the second site to be resynchronized with data that resides at the first site, and remounting a database associated with the second site at the second site.

3. The method of claim 1, further comprising the step of:

if during the membership voting operation it is determined that the first site should be removed from said replication membership, then informing the second site that data is no longer to be replicated at the first site.

4. The method of claim 3, wherein the step of informing comprises:

at the second site informing a file server associated with the second site or the second server that data is no longer to be replicated at the first site.

5. The method of claim 1, wherein the determination of which of the first server and the second server associated with the second site should be removed from said replication membership comprises determining which of the first server or the second server is more important or more reliable.

6. The method of claim 1, further comprising the step of establishing a particular device as a quorum device, and wherein the step of initiating a membership voting operation comprises the steps of:

notifying the quorum device that the write operation could not be successfully performed; and

the quorum device determining which of the first server and a second server associated with the second site should be removed from said replication membership.

7. The method of claim 6, wherein the quorum device comprises a plurality of mirrored devices, and the step of notifying the quorum device is performed by a primary file server, wherein the primary file server is a file server, associated with one of the plurality of sites, through which all other files servers associated with other sites in the plurality of sites communicate with the quorum device.

8. The method of claim 1, wherein the indication that the write operation could not be successfully performed at the second site is an input/output error that is received at the first server.

9. The method of claim 1, further comprising the step of:

if a particular site of the plurality of sites becomes inoperable, then initiating recovery of the particular site after it is determined that all messages transmitted from the particular site to each other site of the plurality of sites have been received at their destination.

10. A machine-readable medium carrying one or more sequences of instructions for mirroring data between a plurality of sites, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

establishing a replication relationship between the plurality of sites including a first site and a second site;

replicating at least some changes made at any site of said plurality of sites at each other site of said plurality of sites;

a first server associated with the first site requesting performance of a write operation;

in response to said request, performing the write operation at the first site, and sending a message to request that the write operation be mirrored at the second site;

the first server receiving an indication that the write operation could not be successfully performed at the second site;

in response to the indication, the first server initiating a membership voting operation to determine which of the first server and a second server associated with the second site should be-removed from said replication membership; and

if it is determined that the second server associated with the second site should be removed from said replication membership, then the first server sending a message to indicate that write operations are no longer to be replicated at said second site.

11. The machine-readable medium of claim 10, wherein execution of the one or more sequences of instructions by the one or more processors causes the one or more processors to further perform the steps of:

the second site rejoining the replication relationship; and

in response to said second site rejoining the replication relationship, causing data associated with the second site to be resynchronized with data that resides at the first site, and remounting a database associated with the second site at the, second site.

12. The machine-readable medium of claim 10, wherein execution of the one or more sequences of instructions by the one or more processors causes the one or more processors to further perform the step of:

if during the membership voting operation it is determined that the first site should be removed from said replication membership, then informing the second site that data is no longer to be replicated at the first site.

13. The machine-readable medium of claim 12, wherein the step of informing comprises:

at the second site informing a file server associated with the second site or the second server that data is no longer to be replicated at the first site.

14. The machine-readable medium of claim 10, wherein the determination of which of the first server and the second server associated with the second site should be removed from said replication membership comprises determining which of the first server or the second server is more important or more reliable.

15. The machine-readable medium of claim 10, wherein execution of the one or more sequences of instructions by the one or more processors causes the one or more processors to further perform the step of:

establishing a particular device as a quorum device, and

wherein the step of initiating a membership voting operation comprises the steps of;

notifying the quorum device that the write operation could not be successfully performed; and

the quorum device determining which of the first server and a second server associated with the second site should be removed from said replication membership.

16. The machine-readable medium of claim 15, wherein the quorum device comprises a plurality of mirrored devices, and the step of notifying the quorum device is performed by a primary file server, wherein the primary file server is a file server, associated with one of the plurality of sites, through which all other files servers associated with other sites in the plurality of sites communicate with the quorum device.

17. The machine-readable medium of claim 10, wherein the indication that the write operation could not be successfully performed at the second site is an input/output error that is received at the first server.

18. The machine-readable medium of claim 10, wherein execution of the one or more sequences of instructions by the one or more processors causes the one or more processors to further perform the step of:

if a particular site of the plurality of sites becomes inoperable, then initiating recovery of the particular site after it is determined that all messages transmitted from the particular site to each other site of the plurality of sites have been received at their destination.