The embodiments described herein are directed to efficient merging of metadata managed by a volume layer of a storage input/output (I/O) stack executing on one or more nodes of a cluster. The metadata managed by the volume layer, i.e., the volume metadata, is illustratively organized as a multi-level dense tree metadata structure, wherein each level of the dense tree metadata structure (dense tree) includes volume metadata entries for storing the volume metadata. The volume metadata entries of an upper level of the dense tree metadata structure are merged with the volume metadata entries of a next lower level of the dense tree metadata structure when the upper level is full. The volume metadata entries of the merged levels are organized as metadata pages and stored as one or more files on the SSDs.