You can use the installed database or an existing database as the monitoring database. Irrespective of which type of database you deploy, you want to set it up in a way that avoids unduly impacting runtime performance of the system.
Care should be taken to have adequate set up for monitoring so that the system performance is within acceptable boundaries. Excessive monitoring has a detrimental impact to performance of each server in the cluster. Monitoring is performed on separate threads in the server, so monitoring requests do not directly impact Unwired Platform performance. However, the effect of these background threads has an overall impact to the server. For example, in the default monitoring profile, expect a three percent increase to response times and throughput. For information about the features of monitoring, see the Runtime Monitoring chapter. For setup steps, see Creating and Enabling a Monitoring Profile in Sybase Control Center online help.