The Serialize to file step, formerly known as Cube File Output, stores rows of data in a binary format in a file. The binary format has an advantage over a text (flat) file because the content does not have to be parsed when read back. The metadata is stored in the file as well.
The Serialize to file step supports a write-once access pattern, and does not support appending to existing files.
Note: For safety, this step should not be shared between different versions of Pentaho Data Integration and is only meant for short lived temporary data.