The default location of all libraries of a particular site is ~/<sitename>/media. You can customize the location by entering a path in Site Manager -> Settings -> Content -> Media -> Custom media libraries folder.
You can enter the folder location in the following formats:
•physical path - e.g. c:\Libraries.
•virtual path - e.g. ~/Libraries.
•UNC path - e.g. \\<server name>\Libraries.
If you enable the Use site-specific subfolders for custom media libraries folder option, media library files will be stored in a sub-folder named as the site code name under the custom files folder, i.e. <custom media libraries folder>/<site code name>.
In case that you are running the system on a web farm and have the same UNC root defined on all servers, it is necessary to add the following key into your web.config in order for the files stored in the libraries not to be transferred when synchronizing the web farm content: