FLEXIBLE REMOTE DATA MIRRORING

• US 20100049798A1
• Filed: 11/04/2009
• Published: 02/25/2010
• Est. Priority Date: 11/11/1999
• Status: Active Grant

• Current Assignee: Intellectual Ventures Assets 78, LLC (Intellectual Ventures LLC)
• Original Assignee: Miralink Corporation
• Inventors: McCabe, Ron, Schroeder, David J., Church, Robert, Card, Stuart W., Camp, Tracy
• Granted Patent: US 8,762,328 B2
• Time in Patent Office: Days
• US Class Current: 709/203
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/2058 using more than 2 mirrored copies
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2069 Management of state, configuration or failover
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 2201/835 Timestamp
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 2201/855 Details of asynchronous mirroring using a journal to transfer not-yet-mirrored changes
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0626 Reducing size or complexity of storage systems
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• 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 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

Methods, systems, and configured storage media are provided for flexible data mirroring. In particular, the invention provides many-to-one data mirroring, including mirroring from local servers running the same or different operating systems and/or file systems at two or more geographically dispersed locations. The invention also provides one-to-many data mirroring, mirroring with or without a dedicated private telecommunications link, and mirroring with or without a dedicated server or another server at the destination(s) to assist the remote mirroring unit(s). In addition, the invention provides flexibility by permitting the use of various combinations of one or more external storage units and/or RAID units to hold mirrored data. Spoofing, SCSI and other bus emulations, and further tools and techniques are used in various embodiments of the invention.

Claims

1. A system for storing data comprising:

an interface configured to receive a plurality of data changes, the data changes indicating a change in data stored on a storage volume of a host;

a meta-data block generator configured to generate a plurality of meta-data blocks, each meta-data block associated with at least one of the data changes, the meta-data blocks indicating a time that data changes associated with the meta-data blocks were made on the storage volume relative to other data changes;

a local buffer configured to store the data changes and the meta-data blocks;

a communications link coupled to the local buffer; and

a remote buffer coupled to the communications link and configured to receive and store the data changes and the associated meta-data blocks from the local buffer.

2. The system of claim 1, wherein each meta-data block includes a timestamp associated with the associated data changes, and a sequence number associated with the associated data changes.

3. The system of claim 1, further comprising:

a communications link monitor configured to monitor a status of the communications link;

wherein the local buffer is configured to pause transmission of the data changes and associated meta-data blocks if the communications link monitor detects an interruption of the communications link.

4. The system of claim 3, wherein the local buffer is further configured to resume transmission of the data changes and associated meta-data blocks if the communications link monitor detects that the communications link is restored.

5. The system of claim 1, further comprising:

a communications link monitor configured to monitor a status of the communications link;

wherein the local buffer is configured to adjust a rate of transmission of the data changes and associated meta-data blocks in response to the communications link monitor detecting a change in available bandwidth.

6. The system of claim 1, further comprising:

a remote mirror including all of the data stored on the storage volume at an associated point in time;

wherein the remote buffer is configured to update the remote mirror using the data changes.

7. The system of claim 6, wherein the remote buffer is configured to store in the remote mirror an oldest data change of the data changes stored in the remote buffer according to the associated meta-data blocks and remove the oldest data change from the remote buffer.

8. The system of claim 6, further comprising:

a volume reconstructor configured to generate data of the storage volume from a previous point in time from the remote mirror, and at least one of the data changes and the meta-data blocks associated with the at least one data change.

9. The system of claim 1,

wherein the local buffer is configured to maintain a particular data change in the local buffer until after an acknowledgement indicating that the particular data change was stored in the remote buffer is received by the local buffer.

10. The system of claim 9, further comprising:

a local mirror configured to store the data changes and including all of the data stored on the storage volume at a point in time;

wherein the interface is further configured to transmit the data changes to the local buffer and the local mirror.

11. The system of claim 1, further comprising:

a remote mirror including all of the data stored on the storage volume at a point in time;

wherein the local buffer is configured to maintain a particular data change in the local buffer until after an acknowledgement indicating that the particular data change was stored in the remote mirror is received by the local buffer.

12. The system of claim 11, wherein the local buffer is configured to remove the particular data change from the local buffer when the acknowledgement indicating that the particular data change was stored in the remote mirror is received by the local buffer.

13. The system of claim 11, wherein the local buffer is configured to remove the particular data change from the local buffer when a signature associated with the particular data change and received by the local buffer is validated.

14. The system of claim 1, further comprising:

a remote mirror including all of the data stored on the storage volume at a point in time;

wherein the remote buffer is configured to store the data changes in the remote mirror in an order indicated by the associated meta-data blocks.

15. The system of claim 1, further comprising:

a plurality of hosts, each host including a primary storage volume;

a plurality of first mirroring units, each mirroring unit coupled to an associated host and configured to mirror the primary storage volume of the associated host, such that each host is coupled its own first mirroring unit; and

a second mirroring unit coupled to the first mirroring units, the second mirroring unit configured to mirror the mirrored primary storage volumes of the first mirroring units;

wherein;

a first mirroring unit of the plurality of first mirroring units includes the interface, the meta-data block generator, and the local buffer, where the first mirroring unit is coupled to its corresponding host through the interface.

16. The system of claim 15, wherein the second mirroring unit locks access to a mirror of a mirrored primary storage volume in response to an access by an associated first mirroring unit.

17. The system of claim 1, wherein:

the storage volume is divided into a plurality of blocks; and

each data change indicates at least one of the blocks of the storage volume with the data that was changed in the storage volume.

18. The system of claim 17, further comprising:

a remote mirror divided into a plurality of blocks, the blocks of the remote mirror corresponding to the blocks of the storage volume on a one-to-one basis; and

wherein the remote buffer is configured to store the data changes in the corresponding blocks of the remote mirror.

19. The system of claim 17, further comprising:

a local mirror divided into a plurality of blocks;

wherein the local buffer is configured to store a particular data change and associated meta-data block only if data in a block of the local mirror that corresponds to a block associated with the data change is different from corresponding data in the data change.

20. The system of claim 1, wherein:

the interface is a standard storage subsystem bus interface; and

the data changes are write requests received through the standard storage subsystem bus interface.

21. The system of claim 20, further comprising:

a local mirror coupled to the interface through a second standard storage subsystem bus interface;

wherein the interface is configured to provide a first copy of the write request to the local mirror through the second standard storage subsystem bus interface and to provide a second copy of the write request to the local buffer.