How does RBS handle files deleted in SharePoint?

Question

I've got RBS configured - and apparently working - in my dev farm, but have a question about how it handles file deletion. If I check the overall size of my blobstore folder (let's say 'C:\Blobstore') both before and after uploading a file over the specified size (100KB), I can see the size of the folder increase. However, if I do the same thing before and after deleting a file, I see no change in size for the blobstore folder. I confirmed the following:

• RBS appears to be working correctly
• File did not exist before RBS - it was uploaded afterwards and added to blobstore size
• Both Recycle Bins are disabled for the web application

Under these conditions, shouldn't the blobstore folder decrease by the same (or a similar) amount as the deleted file?

Environment: SharePoint 2013 Enterprise, one WFE running all services, separate SQL server

Answer 1

This is expected behavior.

RBS is supported by a remote BLOB store Maintainer (RBS Maintainer), which is a process performing garbage collection besides RBS other maintenance tasks.

The deletion behavior is based on the following:

Any BLOB references that are present in the RBS auxiliary tables but absent in any RBS column in application tables, as well as BLOBs that are not present in any RBS column and were created before the Orphan Cleanup Time Window, described below, are assumed to be deleted by the application and will be garbage-collected.

Because passive garbage collection tabulates BLOB references from the RBS columns of an application's tables, every RBS column should have a valid index before it can be registered with RBS.

This lazy garbage collection is performed by the RBS Maintainer tool. It should be scheduled to run at non-busy times to reduce the impact on normal database operations.

The garbage collection has no default setting for a run schedule, but it's something that should be defined as part of the RBS's installation.

Reference: Maintaining Remote BLOB Store.