For combining virtual mapping metadata and physical space mapping metadata in a storage system by a processor device in a computing environment, data and metadata are maintained into separate virtual streams. The separate virtual streams include a metadata stream for the metadata and a data stream for the data. Metadata for each input/output (I/O) operation received is determined using a linear function operation, the function operation being an offset of the metadata in the metadata stream that is equal to the I/O operation multiplied by a maximal metadata ratio. The metadata is allocated on the metadata stream and the metadata stream is divided into fixed size block that is responsible for describing a size of a logical space, where the logical space is equal to one divided by the maximal metadata ratio, and it is determined if the metadata has been previously loaded.