Flexible synchronous file system replication

A non-transitory computer-readable storage device storing computer-executable instructions that in response to execution cause a file system replication system to perform operations, the operations comprising:

• generating a spatial query that identifies a primary directory tree in a file system (FS) in which to search for a changed file, where the FS stores a file in a first location in a first data storage device, where the FS includes a metadata archive, where the metadata archive includes a spatial database, and where the metadata archive stores metadata about a file stored in the FS in the spatial database;
• querying the metadata archive with the spatial query;
• receiving a response to the spatial query from the metadata archive, where the response indicates a range of the primary directory tree in which a changed file may be found;
• generating a scan filter based, at least in part, on the response to the spatial query from the metadata archive, where the scan filter defines a portion of the primary directory tree to search for a changed file, where the portion of the primary directory tree is smaller than the primary directory tree;
• scanning the portion of the primary directory tree defined by the scan filter for a changed file;
• and
• upon detecting a changed file:
• replicating the changed file to a second, different location.

An apparatus for replicating a file system (FS) that stores a file in a first location in a first data storage device, the apparatus comprising:

• a memory configured to store a replication policy;
• a processor;
• a set of circuits;
• and
• an interface that connects the memory, the processor, and the set of circuits, the set of circuits comprising:
• a query circuit configured to generate a spatial query that identifies a primary directory tree in the FS in which to search for a changed file, where the query circuit generates the spatial query based, at least in part, on the replication policy, and
• where the query circuit is further configured to receive a response to the spatial query from the FS, where the response identifies a range of the primary directory tree in which a changed file may be found;
• a scan filter circuit configured to:
• generate a scan filter based, at least in part, on the response to the spatial query, where the scan filter defines a portion of the primary directory tree to search for a changed file, where the portion of the primary directory tree is smaller than the primary directory tree;
• and
• a replication circuit configured to:
• scan the portion of the primary directory tree defined by the scan filter for a changed file, and
• upon detecting a changed file:
• replicate the changed file from the first location to a second, different location.