Handling failures in distributed data system

A system comprising:

• at least one hardware processor;
• and
• a non-transitory computer-readable storage medium having program code embodied therewith, the program code executable by said at least one hardware processor to
• prior to performing a planned i-th data movement in a distributed data system comprising a plurality of storage sites, generate (i) a first map of current locations of data item replicas following an immediately-preceding (i−1)-th data movement, wherein said first map is indexed as i−1, (b) a first timestamp associated with a completion of said (i−1)-th data movement, wherein said first timestamp is indexed as i−1, and (c) a second map of expected locations of data item replicas following said i-th data movement, wherein said second map is indexed as i;
• implement said i-th data movement;
• generate, upon performing said i-th data movement, a second timestamp associated with a completion of said i-th data movement, wherein said second timestamp is indexed as i;
• and
• if a failure occurs with respect to at least one of said storage sites during said i-th data movement, determine a completion status of said i-th data movement, based on a comparison between said indexing of said second map and said indexing of said second timestamp.

A computer program product comprising a non-transitory computer-readable storage medium having program code embodied therewith, the program code executable by at least one hardware processor to:

• prior to performing a planned i-th data movement in a distributed data system comprising a plurality of storage sites, generate (i) a first map of current locations of data item replicas following an immediately-preceding (i−1)-th data movement, wherein said first map is indexed as i−1, (b) a first timestamp associated with a completion of said (i−1)-th data movement, wherein said first timestamp is indexed as i−1, and (c) a second map of expected locations of data item replicas following said i-th data movement, wherein said second map is indexed as i;
• implement said i-th data movement;
• generate, upon performing said i-th data movement, a second timestamp associated with a completion of said i-th data movement, wherein said second timestamp is indexed as i;
• and
• if a failure occurs with respect to at least one of said storage sites during said i-th data movement, determine a completion status of said i-th data movement, based on a comparison between said indexing of said second map and said indexing of said second timestamp.