Method and system for backing up and restoring data of a node in a distributed system

A method for backing up and restoring contents of a data set of a node in a distributed system, comprising:

• initiating a back up operation of an original data set, original the data set having state data indicating that the original data set is original data rather than backup data;
• before making a backup copy of the original data set, changing state data of the original data set to indicate that the original data set backup data;
• after changing the state data of the original data set, taking a snapshot of the contents of the original data set, including the state data indicating that the original data set is backup data, to generate a backup copy, the contents of the data set including a plurality of changes each identified by a replication identification number of the node and a serial number;
• and
• after taking the snapshot, resetting the state data of the original data set to again indicate that the original data set is original data rather than backup data.

A computer system for acting as a node in a distributed system, the computer system comprising:

• a data manager for maintaining a data set containing a plurality of changes each identified by a replication identification number of the node and a serial number, the original data set having state data indicating that the original data rather than backup data;
• a replication server for replicating changes made to the original data set to other nodes in the distributed system;
• a backup server for generating a backup copy of the original data set, the backup server being programmed to:
• (i) cause the state data of the original data set to be set to indicate that the original data set is backup data before making a backup copy of the original data set, (ii) after changing the state data of the original data set, take a snapshot of the contents of the original data set, including the state data indicating that the data set is backup data, to generate the backup copy of original data set, and (iii) cause the state data of the original data set to be reset after taking the snapshot to again indicate that the original data set is original data rather than backup data.