You can Optimize SharePoint Storage with remote Blob Storage (RBS) [MSDN].
There are two kinds of RBS providers, local and remote. The location in which an RBS provider stores the BLOB data depends on the provider that you use. In the case of the FILESTREAM provider, the data is not stored in the .mdf file. Instead, it is stored in another folder that is associated with the database.
Local RBS provider
A local provider stores the BLOBS outside the database but on the same server that is running SQL Server. You can conserve resources by using the local RBS FILESTREAM provider to put the extracted BLOB data on a different (that is, less resource-intensive) local disk. Because the BLOBs are stored in the same Filegroup as the metadata, SharePoint Server 2010 features, such as backup and restore in Central Administration, can be used.
The RBS FILESTREAM provider is available through the SQL Server Remote BLOB Store installation package from the Feature Pack for SQL Server 2008 R2. The RBS FILESTREAM provider uses the SQL Server FILESTREAM feature to store BLOBs in an additional resource that is attached to the same database and stored locally on the server. The FILESTREAM feature manages BLOBs in an SQL database by using the underlying NTFS file system.
Remote RBS provider
A remote RBS provider stores the BLOBs on a separate server. This is typically on a separate volume on the same network as the database server.
Because the BLOBs are not stored in the same Filegroup with the metadata, some SharePoint 2013 features — for example, backup and restore in Central Administration — cannot be used with remote RBS providers. The metadata and the BLOBs must be managed separately. For more information about what features can be used with the provider, contact the provider manufacturer.
Configure RBS with SharePoint 2013