In V8 and above,filestore is used by default.. no need for extra setup

 There is a configuration parameter called data_dir which stores data in local storage and adds link to that data from the db. So set data_dir (like data_dir = /filestore) in odoo.conf file

see the filestore concept in odoo. Just google it.

You may choose to store attachments on the file system by setting an ir.config.parameter (Settings->Technical->Parameters-System parameters) named ir_attachment.location