Methods and systems for seamless tiering in a distributed storage system

A method for processing requests, the method comprising: receiving, from a client application node and by a metadata node, a request for a data layout, determining a QoS tag associated with the request, identifying at least one file system block (FSB) in a sparse virtual space, wherein the FSB is mapped to a location in a storage pool that is associated with the QoS tag, generating the data layout based on the at least one identified FSB; and providing the data layout to the client application, wherein the client application node uses the data layout to directly write data to the location in the storage pool, wherein the metadata node does not participate in the writing of the data to the location in the storage pool.