Hard job to see all
In openkm-ds.xml ( it's in deploy %jboss_home/server/default/deploy folder ) you've got all databases defined ( for their names you could understand what have in )
The files (blobs) are stored by default - if you've not changed the default configuration - under %Jboss_home%/repository folder structure. It's not the typical operating system structure, reason why you could not accessing directly to repository files ( blobs ) directly from your hard disk server ( you could have diferent configurations, depending first starting up and repository.xml configuration file ).