We have have noticed the Derby database appears to be running even though we have specified an external DB2 database for OM Web Viewer 12.1.
We are using DB2 and we have set the appropriate properties in the WVProfile.properties file yet Derby still seems to be running since we can see new entries in the log directory at <CAOMWV12_HOME> /database/RunTimeCacheDB.
OM Web Viewer 12.1 uses the Apache Derby database internally so that is what you are seeing at that location.