What happens if we add multiple MiD servers to the Discovery Functionality

[Mounica6]

Hello Everyone,

We are trying to discover SNMP and Windows devices for similar IP ranges, and it's taking a long time to complete the discovery scan. So we decided to use "behavior type" under MID server selection method in the Discovery Schedules & rather than using separate Discovery schedules, we are planning to use a single schedule which runs both SNMP & Windows together. But, there is a problem which is  - SNMP & Windows devices have different MID servers to discover the data.  Now, while creating the "Discovery Functionality"  we have an option to add multiple MID servers as it is a List Collector field. Now, we are not sure how multiple MID servers added in the Discovery functionality would get the data into the system. Will there be load balancing between the two? Or will the MID servers get the data as per their configuration, i.e., 1 MID getting SNMP separately and the other Windows? If anyone has an idea, please throw some light. I've searched many documents, but couldn't get the significance of the Lookup field for MID servers under the Discovery Functionality form.

[Nilesh Pol · Accepted solution]

@Mounica6 

If you add multiple MID servers it will act as POOL, meaning during the discovery when this functionality is in the pitcher the platform will pick one MID from the pool using round robin load balancing. if the a MID server is down the next one in the pool tried.

This method gives us high availability with load distribution. 

[Harish Bainsla]

Hi @Mounica6 

If you add multiple MID Servers in Discovery Functionality, ServiceNow will do automatic load balancing across them.
• The MID servers are not tied to protocol (SNMP/Windows). Instead, any MID in the pool can pick up probes based on availability.
• This improves performance because the workload gets distributed

Let take Example there are Two Mid Server

MID Server A (Windows host)
• MID Server B (Linux host)
You run a Discovery schedule for IP range 10.10.0.0/24 (mix of Windows & SNMP devices).
• ServiceNow sends discovery probes.
• MID A process 30 devices (both Windows + SNMP).
• MID B process 20 devices (both Windows + SNMP).
 They distribute the load automatically. It is not restricted that MID A = Windows only and MID B = SNMP only.

For more Understanding in depth check below video 

https://youtu.be/E7rSxg97NbQ?si=hNwy3y1rdKMizHp9

If my answer helps you mark helpful and accept solution

[Ravi Gaurav]

Hi @Mounica6 

When you use a single discovery schedule with behavior type, ServiceNow decides which MID server to use based on the discovery functionality definitions. If you have assigned one MID server for SNMP and another for Windows in their respective functionalities, the platform will automatically route SNMP probes to the SNMP MID and Windows probes to the Windows MID. If multiple MID servers are assigned to the same functionality, then discovery load balances the work between them in a round-robin fashion.

In short, there is no mix between SNMP and Windows—each MID handles the functionality it is configured for, and only within the same functionality do multiple MIDs share the load.