gkTotalDBDiskUsage used to be just the total size of the uag database. However it is fixed in 3.2.5 and 3.3.0 so it is the total size of ALL the MySQL databases after those.
gkLogDiskSize is the size of the database log /var/lib/mysql/uag/log.ibd. gkLogRecords is the value returned by this query: SELECT COUNT(log_id) FROM log WHERE machine_id = unhex('%s')