Asymmetrical load balancing for mirrored storage volumes

• US 20040034751A1
• Filed: 08/11/2003
• Published: 02/19/2004
• Est. Priority Date: 08/19/2002
• Status: Active Grant

• Current Assignee: Adaptec Incorporated (Steel Partners Holdings LP)
• Original Assignee: Aristos Logic Corp. (Steel Partners Holdings LP)
• Inventors: Horn, Robert L., Wilkins, Virgil V.
• Granted Patent: US 7,162,579 B2
• Time in Patent Office: Days
• US Class Current: 711/158
• CPC Class Codes: G06F 2206/1012 Load balancing
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

A network storage system includes a network storage system controller/virtualizer which includes at least one transaction processor. When a host access request is received by the network storage system controller/virtualizer, the transaction processor calculates one or more cost functions. In one exemplary embodiment, a cost function associated with storage system volume load and a cost function associated with communication path load are calculated. The cost function result(s) are utilized by the storage system controller/virtualizer to form a request for servicing the host access request while balancing the load of the network storage system.

Claims

1. A method for reading data from a networked storage system, comprising:

receiving, from a host, a host access command for reading data;

determining a plurality of storage locations having the data;

calculating at least one cost function for each of said plurality of storage locations;

building a storage access command for optimizing reading of one of said plurality of storage locations having the data based on a set of results of said at least one cost function;

accessing one of said plurality of storage locations having the data by processing the storage access command; and

returning said data to the host to service the host access command.

2. The method of claim 1, wherein said at least one cost function comprises a cost function based on storage volume load.

3. The method of claim 2, wherein said storage access command was built directed to a storage volume having the data and having minimal loading.

4. The method of claim 2, wherein said storage volume load is calculated as a weighted function based upon at least a number of commands pending on a storage volume.

5. The method of claim 2, wherein said storage volume load is calculated as a weighted function based upon at least a number of sectors per volume.

6. The method of claim 2, wherein said storage volume load is calculated as a weighted function based upon at least a stripe size of said storage volume.

7. The method of claim 2, wherein said storage volume load is calculated as a weighted function based on at least a number of bad sectors on a storage volume.

8. The method of claim 1, wherein said at least one cost function comprises a cost function based upon communication path load.

9. The method of claim 8, wherein said storage access command was built directed to using a network path having minimal loading.

10. The method of claim 8, wherein said communication path load is calculated as a weighted function based upon at least a number of command pending on a network path.

11. The method of claim 8, wherein said communication path load is calculated as a weighted function based upon at least a number of sectors per path.

12. A network storage system, comprising:

a plurality of network paths;

a plurality of storage volumes, each of said storage volumes being coupled to at least two network paths;

a controller coupled to each of said plurality of network paths;

wherein when said controller receives a host read command, said controller;

determines a set of locations containing a copy of said data requested by said host read command;

calculates at least one cost function associated with each of said copies of said data;

builds an access command to a copy of said data based on a results of said at least one cost function; and

retrieves a copy of said data by executing said access command to service said host read command.

13. The network storage system of claim 12, wherein said controller comprises at least one transaction processor.

14. The network storage system of claim 13, wherein said controller comprise two transaction processors.

15. The network storage system of claim 14, wherein one of said two transaction processors calculates a first cost function based upon storage volume load.

16. The network storage system of claim 14, wherein another one of said two transaction processors calculates a second cost function based upon communication path load.

17. The network storage system of claim 13, wherein each one of said transaction processors comprise a map scan engine for determining each location of said read data.

18. The network storage system of claim 13, wherein each one of said transaction processors include a means for determining a storage volume load.

19. The network storage system of claim 13, wherein each one of said transaction processors include a means for determining a communications load.

20. The network storage system of claim 13, wherein each one of said transaction processors include a means for building an access command based on results from said cost functions.