A feature of using the Remote Blob Storage with SharePoint 2010 (FILESTREAM provider in SQL Server 2008) is that document versions do not always create a new full copy of the original file, as it would in a non-RBS environment.
This is a huge improvement since 5 versions of a 10 MB file where only metadata is changed would result in 50 MB purely for file contents (not counting metadata storage size).
SharePoint 2010 without RBS
The files are stored in the Content Database in [AllDocStreams] in a varbinary field called Content. Each version counts as a record and the Contents field is replicated, even if only a metadata change occurred.
SharePoint 2010 with RBS
The files are stored on the file system. Each file or version record in the Content Database (table [AllDocStreams]) maintains a pointer to the RbsId. As you see in the screen below multiple versions still point to the same identifier of the blob, as long as the actual file hasn’t changed.
Very nice !