There are several requirements for adding a database server to the cloud.
The current number of cloud servers must not match the maximum number of cloud servers that can run on a host.
When a cloud server is created, it is named according to the host it is running on and the order in which it was created on the host. For example, if you create a cloud server on the host myhost, and it is the third cloud server that you have created on that host, the name of the cloud server is myhost#3. If you later delete myhost#3 and then create another cloud server, then the name of the new cloud server is myhost#4.