Job Servers continuously disappering from Job Queue Info page and DBQueue is not processing

I think you misinterpret the view "JobServers". As described here https://support.oneidentity.com/technical-documents/identity-manager/9.1.1/process-monitoring-and-troubleshooting-guide#TOPIC-1990447 this view shows the Job queue contents sorted by executing servers. At the first hierarchy level, all Job servers are displayed, with their counts of the different processes, that exist in the Job queue for the Job server. If a Job server node is opened, the process tasks are listed and the number of process step per process task is shown. The process steps are listed by start time under the process task node.

Therefore the list of servers shows only those JobServers that do have some task to process in the JobQueue.

To determine the status of your JobServers using the View > Server state as described here https://support.oneidentity.com/technical-documents/identity-manager/9.1.1/process-monitoring-and-troubleshooting-guide/5#TOPIC-1990475

Thank you for quick reply Markus, I understand the process. 

Best regards