FLEXIBLE REMOTE DATA MIRRORING

• US 20070168518A1
• Filed: 03/19/2007
• Published: 07/19/2007
• 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, Camp, Tracy
• Granted Patent: US 7,941,501 B2
• Time in Patent Office: Days
• US Class Current: 709/226
• 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 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 11/2079 Bidirectional techniques
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 3/0614 Improving the reliability 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]

Abstract

Methods, systems, and configured storage media are provided for flexible data mirroring. In particular, the invention provides local-remote role reversal, implementation of hot standby server status through a “media not ready” signal, several alternate buffer contents and buffering schemes, transactioning, many-to-one mirroring through use of “virtual” remote mirroring units, identification of frequently accessed data without application-specific knowledge but based instead on an application'"'"'s logged and analyzed behavior, and use of the secondary server in a non-authoritative manner.

Claims

1. A method for data mirroring, comprising:

receiving change data from a source, the change data received in a mirroring unit; and

storing a changed logical block number in a buffer in the mirroring unit, the changed logical block number indicating a logical block on the source corresponding to the change data.

2. The method of claim 1, further comprising storing change data in the buffer if a remaining storage in the buffer is greater than a threshold, wherein storing the changed logical block number in the buffer further comprises storing the changed logical block number in the buffer instead of the change data if the remaining storage in the buffer is less than the threshold.

3. The method of claim 1, wherein receiving the change data from the source further comprises receiving the change data from a local mirror, the local mirror including a mirror of a storage volume of a host.

4. The method of claim 1, wherein receiving the change data from the source further comprises receiving the change data from a host, the change data corresponding to a data change on a storage volume of the host.

5. The method of claim 1, wherein:

receiving the change data further comprises receiving the change data corresponding to a change in a block referenced by a changed logical block number entry already in the buffer; and

storing the changed logical block number in the buffer further comprises changing the changed logical block number entry from the changed logical block number to another logical block number, wherein data in the block before the change is stored in a location referenced by the other logical block number.

6. The method of claim 1, wherein storing the changed logical block number in the buffer further comprises storing the changed logical block number in the buffer without storing the change data.

7. A method for data storage management, comprising:

creating a set of mirrored data elements in a mirroring unit, the first set of mirrored data elements including all data of a mirrored volume at a first time;

maintaining the set of mirrored data elements; and

maintaining an ordered queue of change data in the mirroring unit, wherein a combination of at least one entry of the ordered queue and the set of mirrored data elements includes all data of the mirrored volume at a second time.

8. The method of claim 7, further comprising:

selecting an entry of the ordered queue; and

storing the set of mirrored data elements as modified by the selected entry and any older entries of the ordered queue in the mirrored volume.

9. The method of claim 7, further comprising:

changing the set of mirrored data elements in response to an oldest entry of the ordered queue; and

removing the oldest entry from the ordered queue.

10. The method of claim 7, wherein maintaining the set of mirrored data elements and maintaining the ordered queue of change data further comprises maintaining the set of mirrored data elements and maintaining the ordered queue of change data on the same physical storage system.