Hi Skip,
If the "Backup Compression" option is enabled in OnLine Backup configuration, the backup files are compressed using the compression utility before being written to disk. Compressed files are saved with a .gz suffix appended to the filename. If disabled, files are saved uncompressed. The default value is enabled.
Host Configuration (NCM) backup increases the SSdb size.
If you run a lot of discoveries you could also be creating AdiscResultSet models which store the results of each run and it could also increase the SSdb size.
Try the database_tally script and look at the number of the "HostConfiguration" and "AdiscResultSet" models.
cd $SPECROOT/vnmsh/sample_scripts/
./database_tally `hostname`