Many unexpected robot inactive alarm after a hub restart

Products

• DX Unified Infrastructure Management (Nimsoft / UIM)

Issue/Introduction

You are seeing immediate inactive alarms as soon as a secondary hub is restarted. Those inactive alarms shouldn't be triggered, because we are just restarting the hub.

Why are they occurring? 

Note: An other associated behavior observed is that the only by restarting this hub, robots failover quite immediately to a secondary hub instead of waiting for the simple hub restart.  

Environment

• DX UIM 23.4.*
• any hub verson

Cause

Possible cause of this issue might be that the primary hub is hitting maximum socket limit (subscribers). (The hub can only handle a maximum of 64 subscribers in a Windows environment due to Windows OS (winsock) limitations on the number of open sockets. )

Resolution

To resolve this issue: 

1. Ensure you are running the latest robot and hub version available for your DX UIM 23.4CU* version.
   Eg. for DX YUIM 23.4CU7 - Upgrade all robots and hubs to 23.4.7
   
   
2. Ensure the primary hub is NOT hitting the limit subscribers (hub queues)
   See: UIM hub subscriber limits and how to monitor the count of subscribers