The default store is called Simple File Store. It stores documents and
media files on
a file system (local or mounted). The store’s default root folder is
[Liferay Home]/data/document_library. You can specify a different root directory from
within System Settings.
Access System Settings by opening the Menu () and navigating to Control Panel → Configuration → System Settings.
In the Platform section, click File Storage. The File Storage page appears.
Click Simple File System Store.
For the store’s Root directory value, specify its absolute path or its path relative to Liferay Home.
Click the Save button.
The document library store switches immediately to the new folder.
You can also use an entirely different method for storing documents and media files:
Simple File System Store: uses the file system (local or a mounted share) to store files.
Advanced File System Store: in addition to using the file system (local or a mounted share) to store files, Advanced File System Store nests the files into folders by version, for faster performance and to store more files.
S3 Store (Amazon Simple Storage): uses Amazon’s cloud-based storage solution.
DBStore (Database Storage): stores the files in the database. DBStore’s file (stored as a blob) size is 1 gigabyte. To store files larger than 1 gigabyte, use Simple File System Store or Advanced File System Store.
These articles explain details for each one.