Just to inform you that there are no published guidelines on the number of monitors it is possible to run within TM ART.
There is a limit to the number of measures that can be written in an hour without overloading the system.
This limit depends on the architecture, hardware resources, and database configuration, and not on a product limitation.
When the limit is reached you must remove non-essential measures or implement a second BMC TM ART instance to reduce the number of measures.
There is some further information on this topic in the "BMC TM ART Administration Module WebHelp" under, "Database Maintenance".
Also,there is no such limitation on the no. of execution servers that TMART Central can handle.
It will depend upon the traffic and data between execution servers to application servers.
10 execution servers can overload an application server if they have too many monitors running on them.
100 can work fine if the monitors are not many or their frequency is less.
As a general advice we can only mention here that there is no functional limit on the number of execution servers that can be added and the frequency and number monitors/transactions that can be scheduled.
Really thanks a lot for your comment. I quite agree with what you said and we all know there are lots of factor on the performance. Say for example, the clock speed of the CPU core already affect the number of workload for an execution server. Not even talking about other in depth factors.
However, customers especially the management level just always want a number. In management level mind, they really think everything in computer world is really just 0 and 1. That's why this kind of question has been raised.