Storing data is disclosed, including: creating a clone of a snapshot comprising a first set of metadata associated with a source data, at least in part by generating for the clone a second set of metadata that includes an active index that is associated with the snapshot and is configured to store metadata associated with data values that are written to the clone; receiving a write operation to write a requested data value to the clone; and in response to the write operation, updating the active index based at least in part on the requested data value.