Currently Cloud Stack has only one active master DB setup. Going forward it should support multiple Master/Slave cluster setup to enable High Availability of the Database.
Scope
To Achieve Active/Active cluster set up (Multiple masters and slaves).
Options Available
MariaDB
Percona Xtra DB (uses Galera cluster)
MHA provided by SkySql
Mysql Active/Active setup with connector specific configuration to read from slaves in case of master goes down