Low latency synchronous replication using an N-way router

• US 8,108,580 B1
• Filed: 04/16/2008
• Issued: 01/31/2012
• Est. Priority Date: 04/17/2007
• Status: Active Grant

• Current Assignee: AmZetta Technologies, LLC (American Megatrends International, LLC)
• Original Assignee: American Megatrends Incorporated
• Inventors: Chatterjee, Paresh, Ranganathan, Loganathan, Balakrishnan, Narayanan, Subramanian, Srikumar
• Primary Examiner(s): Tsai, Henry W. H.
• Assistant Examiner(s): Nam, Hyun
• Application Number:
  US12/104,129
• Time in Patent Office: 1,385 Days
• Field of Search: 710/74, 711/114
• US Class Current: 710/74
• CPC Class Codes: G06F 11/14 Error detection or correction of the data by redundancy in operation G06F11/16 takes precedence
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 11/2076 Synchronous techniques
• CPC Class Codes: G06F 13/00 Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units interface circuits for specific input/output devices G06F3/00 ; multiprogram control therefor G06F9/46; multiprocessor systems G06F15/16
• CPC Class Codes: G06F 13/12 using hardware independent of the central processor, e.g. channel or peripheral processor
• CPC Class Codes: G06F 2201/855 Details of asynchronous mirroring using a journal to transfer not-yet-mirrored changes
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• 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

Technologies for efficient synchronous replication across heterogeneous storage nodes can provide the performance of high-speed storage units while leveraging low-cost and high-capacity backup storage units within the same system. The performance of low-cost, high-capacity hard disks may be improved by initially storing data into sequential physical locations. A sequential journal of I/Os may be used in a replicated secondary node to allow for rapid completion of I/Os. A separate background process can later scatter the sequentially logged I/O data into its proper location for storage. A programmable n-way router can be configured to route I/Os as needed to improve overall performance of the storage unit. A secondary node log device can also be used to provide continuous data protection (CDP). Lastly, packetizing together I/Os prior to delivery to a secondary node may reduce interrupts and context switches in the primary node, thereby improving performance of the storage system.

Claims

1. A method for routing an Input/Output operation (I/O) to support low latency synchronous replication among heterogeneous storage nodes, the method comprising:

receiving the I/O from a source;

routing, within a primary storage node, the I/O to a first data volume manager for local storage;

routing, within the primary storage node, the I/O to a replicating module;

routing, within a secondary storage node, the I/O to a journaling module; and

routing, within the secondary storage node, the I/O from the journaling module to a second data volume manager for local storage, wherein the replicating module is operable to serialize a plurality of I/Os into a sequential journal structure prior to transmitting the sequential journal structure to the secondary storage node.

2. The method of claim 1, wherein the primary storage node has a lower latency than the secondary storage node.

3. The method of claim 1, wherein the primary storage node comprises an SAS hard drive and the secondary storage node comprises a SATA hard drive.

4. The method of claim 1, wherein the replicating module is operable to packetize a plurality of I/Os into an aggregate I/O prior to transmitting the aggregate I/O to the secondary storage node.

5. The method of claim 1, further comprising routing the I/O to a sequential log volume in response to the I/O being a sequential I/O.

6. A method for replicating an Input/Output operation (I/O) from a first storage node to a second storage node, the method comprising:

receiving the I/O at the first storage node;

processing the I/O at the first storage node to store data from the I/O in the first storage node;

replicating the I/O to the second storage node from the first storage node;

storing the operation I/O to a sequential journal in the second storage node; and

retrieving the I/O from the sequential journal to store the data from the I/O in the second storage node, wherein replicating the I/O to the second storage node comprises packetizing a plurality of I/Os into an aggregate I/O prior to transmitting the aggregate I/O to the second storage node.

7. The method of claim 6, wherein the first storage node has a lower latency than the second storage node.

8. The method of claim 6, wherein the first storage node comprises an SAS hard drive and the second storage node comprises a SATA hard drive.

9. The method of claim 6, wherein replicating the I/O to the second storage node comprises serializing a plurality of I/Os into a sequential journal block prior to transmitting the sequential journal block to the second storage node.

10. The method of claim 6, wherein retrieving the I/O from the sequential journal to store the data from the I/O in the second storage node is performed as a background operation.

11. The method of claim 6, further comprising providing continuous data protection to the first storage node by logging, to the second storage node, a data modification made on the first storage node.

12. A non-transitory computer storage medium having computer-executable instructions stored thereon which, when executed by a computer system, cause the computer system to:

determine if execution is on a primary storage node or a secondary storage node;

receive an Input/Output operation from a source;

route the I/O to a first data volume manager for local storage in response to determining that execution is on the primary storage node;

route the I/O to a replicating module in response to determining that execution is on the primary storage node;

route the I/O to a journaling module in response to determining that execution is on the secondary storage node; and

route the I/O from the journaling module to a second data volume manager for local storage in response to determining that execution is on the secondary storage node, wherein the replicating module is operable to packetize a plurality of I/Os into an aggregate I/O prior to transmitting the aggregate I/O to the secondary storage node.

13. The tangible computer storage medium of claim 12, wherein the primary storage node has a lower latency than the secondary storage node.

14. The tangible computer storage medium of claim 12, wherein the primary storage node comprises an SAS hard drive and the secondary storage node comprises a SATA hard drive.

15. The tangible computer storage medium of claim 12, wherein the replicating module is operable to serialize a plurality of I/Os into a sequential journal structure prior to transmitting the sequential journal structure to the secondary storage node.

16. The tangible computer storage medium of claim 12, wherein routing the I/O from the journaling module to the local data volume manager for local storage is performed as an asynchronous I/O.

17. The tangible computer storage medium of claim 12, further causing the computer system to provide continuous data protection to the primary storage node by logging, to the secondary storage node, a data modification made on the primary storage node.