GRID STORAGE SYSTEM AND METHOD OF OPERATING THEREOF

• US 20100153639A1
• Filed: 02/11/2010
• Published: 06/17/2010
• Est. Priority Date: 08/21/2008
• Status: Active Grant

• Current Assignee: Infinidat Ltd.
• Original Assignee: Xsignnet Ltd.
• Inventors: YOCHAI, Yechiel, DORFMAN, Michael, KOPYLOVITZ, Haim, CORRY, Leo
• Granted Patent: US 8,452,922 B2
• Time in Patent Office: Days
• US Class Current: 711/113
• CPC Class Codes: G06F 11/1433 during software upgrading
• CPC Class Codes: G06F 11/1666 where the redundant component is memory or memory area
• CPC Class Codes: G06F 11/2028 eliminating a faulty processor or activating a spare
• CPC Class Codes: G06F 11/2041 with more than one idle spare processing component
• CPC Class Codes: G06F 11/2092 Techniques of failing over between control units

Abstract

The is provided a method of hot backward compatible upgrade of a storage system comprising a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), said addresses constituting an entire address space divided between a plurality of virtual partitions (VPs), and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of at least three data servers, each server having direct or indirect access to the entire address space. The method comprises: a) configuring each certain virtual partition to be controlled by at least two data servers, a primary data server configured to have a primary responsibility for handling requests directed to any range of LBAs corresponding to said certain virtual partition and a secondary data server configured to have a secondary responsibility for handling requests directed to any range of LBAs corresponding to said certain virtual partition and to overtake the primary responsibility for handling respective requests if the primary server fails; b) respectively configuring each data server among the plurality of data servers to have primary responsibility over all LBAs corresponding to at least two virtual partitions and to have secondary responsibility over all LBAs corresponding to at least two other virtual partitions; c) responsive to a shut-down of a data server for an upgrade purpose, i) re-configuring primary responsibility over each VP previously primary controlled by the shut-down server such that it becomes primary controlled by a server previously configured as a secondary server with respect to this VP; ii) re-allocating secondary responsibility over each VP previously secondary controlled by the shut-down server in a manner that each such VP becomes secondary controlled by a server other than the newly assigned server with primary responsibility.

Claims

1. A storage system comprising:

a) a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), said addresses constituting an entire address space divided between a plurality of virtual partitions (VP),

b) a storage control grid operatively connected to the plurality of disk units and comprising a plurality of at least three data servers, each server having direct or indirect access to the entire address space;

wherein each certain virtual partition is configured to be controlled by at least two data servers among said plurality of data servers, a primary data server configured to have a primary responsibility for handling requests directed to any range of LBAs corresponding to said certain virtual partition and a secondary data server configured to have a secondary responsibility for handling requests directed to any range of LBAs corresponding to said certain virtual partition and to overtake the primary responsibility for handling respective requests if the primary server is shut-down for a backward compatible upgrade;

wherein each data server is configured to have primary responsibility over all LBAs corresponding to at least two virtual partitions and to have secondary responsibility over all LBAs corresponding to at least two other virtual partitions; and

wherein the plurality of data servers is pre-configured to enable the following re-assignment of responsibilities if one of the data servers is shut-down for a backward compatible upgrade;

each VP previously primary controlled by the shut-down server becomes primary controlled by a server previously configured as a secondary server with respect to this VP;

each VP previously secondary controlled by the shut-down server becomes secondary controlled by a server other than the newly assigned server with primary responsibility.

2. The storage system of claim 1 wherein the request directed to one or more LBAs is selected from a group comprising respectively directed I/O requests and configuration-related requests.

3. The storage system of claim 1 further configured in response to a request corresponding to a certain virtual partition, to generate a primary cache object in a data server configured as primary with regard to said certain partition and to generate a corresponding redundancy object in a data server configured as secondary with regard to said certain partition, said redundancy object to be deleted upon successful permanent storing of data and/or metadata corresponding to said request while said storing provided by the data server configured as primary, and to be used by said data server configured as secondary for permanent storing said data and/or metadata when overtaking the primary responsibility.

4. The storage system of claim 3 wherein said redundancy object is derived from the primary cache object and needs to be reconstructed in order to enable overtaking the primary responsibility.

5. The storage system of claim 4 wherein said redundancy object is further configured to be handled in a searchable data structure with no need to be incorporated into cache-object control procedures and/or dirty data destaging procedures of the secondary server before overtaking the primary responsibility.

21. The storage system of claim 1 operable in accordance with at least one protocol selected from a group comprising file-access storage protocols, block-access storage protocols and object-access storage protocols.

6. A method of operating a storage system comprising a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), said addresses constituting an entire address space divided between a plurality of virtual partitions (VPs), and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of at least three data servers, each server having direct or indirect access to the entire address space, the method comprising:

a) configuring each certain virtual partition to be controlled by at least two data servers, a primary data server configured to have a primary responsibility for handling requests directed to any range of LBAs corresponding to said certain virtual partition and a secondary data server configured to have a secondary responsibility for handling requests directed to any range of LBAs corresponding to said certain virtual partition and to overtake the primary responsibility for handling respective requests if the primary server is shut-down;

b) respectively configuring each data server among the plurality of data servers to have primary responsibility over all LBAs corresponding to at least two virtual partitions and to have secondary responsibility over all LBAs corresponding to at least two other virtual partitions;

c) responsive to a shut-down of a data server among said plurality of data servers,

i) re-configuring primary responsibility over each VP previously primary controlled by the shut-down server such that it becomes primary controlled by a server previously configured as a secondary server with respect to this VP;

ii) re-allocating secondary responsibility over each VP previously secondary controlled by the shut-down server in a manner that each such VP becomes secondary controlled by a server other than the newly assigned server with primary responsibility.

7. The method of claim 6 wherein the data server is shut-down for upgrade purposes thereby enabling upgrade of said data server whilst retaining protection of data related to any respective request.

8. The method of claim 7 wherein the request directed to one or more LBAs is selected from a group comprising respectively directed I/O requests and configuration-related requests.

9. The method of claim 7 wherein re-allocating secondary responsibility is provided in accordance with a pre-defined allocated table.

10. The method of claim 7 further comprising:

a) responsive to a change in configuration of a certain VP, obtaining by data server having primary responsibility over said certain VP information corresponding to said configuration change;

b) sending said information corresponding to said configuration change to the rest of the data servers in said plurality of data servers.

11. The method of claim 8 further comprising:

a) responsive to successful upgrade of the upgraded data server, informing at least all data servers which have overtaken a responsibility over at least one VP assigned to the upgraded data server before its shut-down that the upgraded server is in operational condition;

b) obtaining by said upgraded server the most updated configuration information with regard to all VPs assigned to said upgraded data server before its shut-down;

c) overtaking by said upgraded data server primary responsibility over all VPs assigned to the upgraded data server before its shut-down as to be controlled with primary responsibility and secondary responsibility over all VPs assigned to the upgraded data server before its shut-down as to be controlled with secondary responsibility.

12. The method of claim 7 wherein the upgraded server overtakes primary and secondary responsibility over a certain. VP, then over another certain VP, and continues the overtaking process until gaining responsibility over all VPs assigned to said upgraded data server before its shut-down.

13. The method of claim 12 wherein the upgraded server overtakes primary responsibility over all VPs assigned to the upgraded data server before its shut-down as to be controlled with primary responsibility, and then overtakes secondary responsibility over all VPs assigned to the upgraded data server before its shut-down as to be controlled with secondary responsibility.

14. The method of claim 12 wherein the upgraded server overtakes primary and secondary responsibility over all VPs controlled by a certain data server with primary or secondary responsibility, then over all VPs controlled by another certain data server with primary or secondary responsibility, and continues the overtaking process until gaining responsibility over all VPs assigned to said upgraded data server before its shut-down.

15. The method of claim 12 wherein at least some operations related to different VPs are provided in parallel.

16. The method of claim 8 further comprising:

a) responsive to a request corresponding to a certain virtual partition, generating a primary cache object in a data server configured as primary with regard to said certain partition;

b) generating a corresponding redundancy object in a data server configured as secondary with regard to said certain partition;

c) using said redundancy object by said data server configured as secondary for permanent storing said data and/or metadata when overtaking primary responsibility over VP when the primary server is shut-down.

19. A computer program comprising computer program code means for performing the method of claim 7 when said program is run on a computer.

20. A computer program as claimed in claim 19 embodied on a computer readable medium.

17. The method of claim 17 wherein said redundancy object is derived from the primary cache object and needs to be reconstructed in order to enable overtaking the primary responsibility.

18. The method of claim 18 wherein said redundancy object is further configured to be handled in a searchable data structure with no need to be incorporated into cache-object control procedures and/or dirty data destaging procedures of the secondary server.