Techniques herein are for accessing non-materialized blocks of a sparse file. A method involves a storage system receiving a storage command to access a sparse file. A combined content of a set of materialized blocks and a header that identifies one or more non-materialized blocks is assembled. The combined content does not comprise a content of the one or more non-materialized blocks. Responsive to the assembling, the combined content is transferred between the storage system and a computer system.