Data export and import generally revolve around the concept of storing data outside the portal, either permanently or temporarily. The portal does this by handling the creation and interpretation of the LAR files.
LAR is short for Liferay Archive. A LAR is mainly used to export the existing page data in a portal group for backup and to import data into another portal group. The following diagram shows the processes of LAR export and import. More specifically, the portal could export both portal core assets and custom assets associated with an existing page or all pages of a given site as a LAR file. The portal could also import from a LAR file, which contains both portal core assets and custom assets associated with an existing page or all pages of a given site into a page or site respectively.
Note that LAR export and import should be used for backup only, and not for upgrading, since the source (portal instance) and the target (portal instance) must have exactly...