The File content store is the default content store.
The File content store saves the files or content items on a file system under the root directory. Within the root directory, the files are stored in numeric directories based upon the creation time of the document. The reason for storing the files in a directory structure is to assist incremental backup. The metadata of your file is stored in the database.
SkyVault Content Services does not modify any file that is stored in the content store. The fileContentStore is pointed to by the ${dir.contentstore} property.