In the following table you will see the reference list of useful transaction codes for mostly used in SAP Basis related to system monitoring.
| Tcodes | Description |
RZ20 | CCMS Alert Monitor |
RZ21 | Configuration of CCMS Alert Monitor |
RZ23N | Central Performance History |
SM04 | List of Active Users |
SM50 | Process Overview |
SM51 | Server List |
SMGW | Gateway Monitor |
SMICM | Internet Communication Manager Monitor |
SMMS | Message Server Monitor |