Grid storage system and method of operating thereof
A method of operating a storage system includes: configuring the address space so that each LBA is assigned to at least two servers among a plurality of at least three servers in a control grid: to a primary server with a primary responsibility for handling requests corresponding to said LBA, and to a secondary server with a secondary responsibility for handling requests corresponding to said LBA. In response to a request corresponding to a certain LBA range, generating by a data server having primary responsibility over the certain LBA range, a primary cache object; identifying a data server configured as a secondary data server with regard to the certain LBA range; and generating a redundancy cache object corresponding to the primary cache object only at the identified secondary data server, the redundancy cache object to be used by the identified secondary data server when taking the primary responsibility.
1. A storage system comprising:
a plurality of disk units adapted to store data at respective ranges of logical block addresses (LBAs), the LBAs constituting an entire address space, and
a storage control grid operatively connected to the plurality of disk units and comprising a plurality of at least three data servers;
wherein each LBA in the entire address space is assigned to at least two data servers among the plurality of at least three data servers: a primary data server configured to have a primary responsibility for handling requests corresponding to said LBA, and a secondary data server configured to have a secondary responsibility for handling requests corresponding to said LBA and to take over the primary responsibility for handling requests corresponding to said LBA if the primary data server fails; and
wherein each data server is further configured, in response to a request corresponding to a certain LBA range under its primary responsibility, to identify a data server configured as a secondary data server with regard to the certain LBA range, to generate a primary cache object, and to enable generating a redundancy cache object corresponding to the primary cache object only at the identified secondary data server, the redundancy cache object to be used by the identified secondary data server, when taking the primary responsibility over the certain LBA range, for permanently storing respective data and/or metadata related to the certain LBA range.
2. The storage system of claim 1 , wherein the request corresponding to the certain LBA range is selected from a group consisting of I/O requests and configuration-related requests.
3. The storage system of claim 1 , wherein said redundancy cache object is derived from the primary cache object and needs to be reconstructed in order to enable taking over the primary responsibility.
4. The storage system of claim 1 , wherein said redundancy cache 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 data server before the secondary data server takes over the primary responsibility.
5. The storage system of claim 1 , wherein the redundancy cache object is derived from the primary cache object as a serialized version of the primary cache object.
6. The system of claim 1 , wherein the redundancy cache object is derived from the primary cache object as a compressed version of the primary cache object.
7. 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, and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of at least three data servers, the method comprising:
configuring the entire address space so that each LBA is assigned to at least two data servers among the plurality of at least three data servers: a primary data server configured to have a primary responsibility for handling requests corresponding to said LBA, and a secondary data server configured to have a secondary responsibility for handling requests corresponding to said LBA and to take over the primary responsibility for handling requests corresponding to said LBA if the primary data server fails; and
in response to a request corresponding to a certain LBA range,
i) generating a primary cache object by a data server having primary responsibility over the certain LBA range;
ii) identifying a data server configured as a secondary data server with regard to the certain LBA range; and
iii) generating a redundancy cache object corresponding to the primary cache object only at the identified secondary data server, the redundancy cache object to be used by the identified secondary data server when taking the primary responsibility over the certain LBA range for permanent storing respective data and/or metadata related to the certain LBA range.
8. The method of claim 7 further comprising deleting the redundancy cache object upon successful permanent storing of data and/or metadata corresponding to the request, the successful permanent storing provided by the primary data server.
9. The method of claim 7 further comprising using the redundancy cache object by the secondary data server for providing permanent storing the data and/or metadata when overtaking primary responsibility.
10. The method of claim 7 , wherein the redundancy cache object is derivation of the primary cache object, the method further comprising reconstructing, before using by the secondary data server, the redundancy cache object into a copy of the primary cache object.
11. The method of claim 10 , wherein the reconstructing is provided responsive to a failure of the primary data server.
12. The method of claim 7 , wherein the redundancy cache object is derived from the primary cache object as a serialized version of the primary cache object.
13. The method of claim 7 , wherein the redundancy cache object is derived from the primary cache object as a compressed version of the primary cache object.
14. The method of claim 7 further comprising handling the redundancy cache object in a searchable data structure with no incorporation into cache-object control procedures and/or dirty data destaging procedures of the secondary data server before taking over the primary responsibility.
15. The method of claim 7 , wherein the request corresponding to the certain LBA range is selected from a group consisting of I/O requests and configuration-related requests.
16. A computer program product for use in conjunction with 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, and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of at least three data servers, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer readable instructions for:
configuring the entire address space so that each LBA is assigned to at least two data servers among the plurality of at least three data servers: a primary data server configured to have a primary responsibility for handling requests corresponding to said LBA, and a secondary data server configured to have a secondary responsibility for handling requests corresponding to said LBA and to take over the primary responsibility for handling requests corresponding to said LBA if the primary data server fails;
in response to a request corresponding to a certain LBA range, generating, by a data server having primary responsibility over the certain LBA range, a primary cache object;
identifying a data server configured as a secondary data server with regard to the certain LBA range; and
generating a corresponding redundancy cache object only at the identified secondary data server, the redundancy cache object to be used by the identified secondary data server when taking the primary responsibility over the certain LBA range for permanent storing respective data and/or metadata related to the certain LBA range.