Unfortunately we do not have these numbers. CMS is nothing we have directly to do with and it seems like CMS do not typically have problems with their (MySQL) databases.
Possibly in the 4th graph the values are not too correct. I do not know for example where MySQL packages distributed with the SuSE distribution count and where MySQL Packages FOR the SuSE distribution count.
Windows on the 4th graph is completely missing so they are counted in the MySQL% packages…
Pros of DRBD are mostly data consistency and reliability. DRBD is a sync replication and you only have your data in one place.
The Cons are Performance and Complexity.