Techniques are provided for shard reorganization in sharded storage systems based on a user-specified dimensional description or key range information. An exemplary method processes data in a sharded distributed data storage system that stores data in a plurality of shards by obtaining a dimensional description for a shard reorganization of the data in the sharded distributed data storage system from a user; and reorganizing a storage of the data on one or more nodes of the sharded distributed data storage system based on the dimensional description. The dimensional description comprises, for example, a semantic description of desired array dimensions or key range information. The semantic description of desired array dimensions comprises a striping of a given data array along one or more of a horizontal face, a vertical face and a sub-array of the given data array. The reorganization can be employed, for example, for key-value objects and multidimensional array objects.