Grid storage system and method of operating thereof

A storage system comprising a plurality of disk units and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of data servers, each server comprising cache memory and non-volatile memory, wherein

• a) a first server among said plurality of data servers is configured:
• i) to have a primary responsibility for handling requests directed to a certain range of logical block addresses (LBAs);
• ii) when operating with primary responsibility, to obtain configuration metadata indicative of configuration and/or changes thereof related to said certain data range and to save said configuration metadata and/or derivatives thereof at one or more disk units among said plurality of disk units in accordance with a predefined criterion;
• iii) when operating with primary responsibility, to save in the first server's cache memory said configuration metadata and/or derivatives thereof obtained between said savings at disk units, thus giving rise to recent configuration changes (RCC) metadata, and to send RCC metadata and/or derivatives thereof to the second server;
• iv) to destage the recent configuration changes metadata to non-volatile memory of the first server if the first server fails;
• b) a second server among said plurality of data servers is configured:
• i) to have a secondary responsibility for handling requests directed to said certain range of LBAs and to overtake the primary responsibility for handling respective requests if the first server fails;
• ii) when operating with primary responsibility while the first server has not been successfully rebooted, to obtain configuration metadata and to save said configuration metadata and/or derivatives thereof at one or more disk units among said plurality of disk units in accordance with a predefined criterion;
• iii) when operating with primary responsibility, to save in the second server's cache memory said RCC metadata and/or derivatives thereof;
• iv) when operating with primary responsibility after successful reboot of the first server and until successful overtaking the respective primary responsibility by the first server, to obtain said configuration metadata, whilst terminating saving said configuration metadata at disk units, to save said RCC metadata in the second server's cache memory, and to send said RCC metadata and/or derivatives thereof to the first server.

A non-transitory computer readable medium storing a computer readable program executable by a computer for causing the computer to perform a process of operating a storage system comprising a plurality of disk units and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of data servers, each server comprising cache memory and non-volatile memory, wherein a first server among said plurality of data servers is configured to have a primary responsibility for handling requests directed to a certain range of logical block addresses (LBAs), and a second server among said plurality of data servers is configured to have a secondary responsibility for handling requests directed to said certain range of LBAs, to overtake the primary responsibility for handling respective requests if the first server fails and to return said primary responsibility to the first server upon the first server's successful reboot;

• the process comprising:
• a) continuously obtaining configuration metadata indicative of configuration and/or changes thereof related to' said certain data range and saving said configuration metadata and/or derivatives thereof at one or more disk units among said plurality of disk units in accordance with a predefined criterion,
• i) wherein said configuration metadata and/or derivatives thereof are obtained and saved by the first server when operating with primary responsibility, and
• ii) wherein said configuration metadata and/or derivatives thereof are obtained and saved by the second server when operating with primary responsibility while the first server has not been successfully rebooted;
• b) continuously saving in server's cache memory said configuration metadata and/or derivatives thereof obtained between said savings at disk units, thus giving rise to recent configuration changes (RCC) metadata,
• i) wherein said RCC metadata and/or derivatives thereof are obtained and saved by the first server, when operating with primary responsibility, and further sent to the second server;
• and
• ii) wherein said RCC metadata and/or derivatives thereof are obtained and saved by the second server when operating with primary responsibility;
• c) destaging the recent configuration changes metadata to non-volatile memory of the first server if the first server fails;
• d) responsive to successful reboot of the first server and until successful overtaking the respective primary responsibility by the first server,
• i) continuously obtaining said configuration metadata by the second server whilst terminating saving said configuration metadata at disk units;
• and
• ii) sending RCC metadata saved in the cache memory of the second server
• and/or derivatives thereof to the first server.

A computer program product comprising a non-transitory computer readable medium storing computer readable program code for causing a computer operating a storage system comprising a plurality of disk units and a storage control grid operatively connected to the plurality of disk units and comprising a plurality of data servers, each server comprising cache memory and non-volatile memory, wherein a first server among said plurality of data servers is configured to have a primary responsibility for handling requests directed to a certain range of logical block addresses (LBAs), and a second server among said plurality of data servers is configured to have a secondary responsibility for handling requests directed to said certain range of LBAs, to overtake the primary responsibility for handling respective requests if the first server fails and to return said primary responsibility to the first server upon its successful reboot;

• the computer program product comprising:
• a) computer readable program code for causing the computer to continuously obtain configuration metadata indicative of configuration and/or changes thereof related to said certain data range and to save said configuration metadata and/or derivatives thereof at one or more disk units among said plurality of disk units in accordance with a predefined criterion,
• i) wherein said configuration metadata and/or derivatives thereof are obtained and saved by the first server when operating with primary responsibility, and
• ii) wherein said configuration metadata and/or derivatives thereof are obtained and saved by the second server when operating with primary responsibility while the first server has not been successfully rebooted;
• b) computer readable program code for causing the computer to continuously save in server's cache memory said configuration metadata and/or derivatives thereof obtained between said savings at disk units, thus giving rise to recent configuration changes (RCC) metadata,
• i) wherein said RCC metadata and/or derivatives thereof are obtained and saved by the first server, when operating with primary responsibility, and further sent to the second server;
• and
• ii) wherein said RCC metadata and/or derivatives thereof are obtained and saved by the second server when operating with primary responsibility;
• c) destaging the recent configuration changes metadata to non-volatile memory of the first server if the first server fails;
• d) computer readable program code for causing the computer to, responsive to successful reboot of the first server and until successful overtaking the respective primary responsibility by the first server,
• i) continuously obtain said configuration metadata by the second server whilst terminating saving said configuration metadata at disk units;
• and
• ii) to send RCC metadata saved in the cache memory of the second server and/or derivatives thereof to the first server.