Service Mapping Mid Servers

[tim_sewell]

How does Service Mapping decide which Mid Server it will use for an end point?

I have 2 Mid Servers configured in different domains, 1 for our Prod domain and 1 for our Test domain.   I created a new business service with an end point to a Web server in the Prod domain.   I would assume that Service Mapping would recognize the domain and choose the correct Mid Server to discover with.   It does not seem to be the case, as the discovery fails with a "Failed to communicate with the WMI collector service on localhost." message.

If I disable the Test domain Mid Server, and run the discovery again, it maps the Web server correctly.   If I start up the Test domain Mid Server service, it fails again...   This leads me to believe that Service Mapping is choosing the Test domain Mid Server by some property or setting.   I have searched all of the documentation I can find on Service Mapping, but I cannot see where this setting may be.   Other steps I have tried:

1. Removed ALL credential affinities and ran a regular ServiceNow Quick Discovery on the Web server, to establish affinity between it and the Prod domain Mid Server.
2. Created a Mid Server IP Range, including the IP of the Web server and assigned it to the Prod domain Mid Server.
3. I assigned the Prod domain Mid Server to be the default Mid Server for Orchestration activities

What am I missing?

[Stijn Verhulst3]

Hi Tim,

Some points to consider:

(1) Does the credential for your web server apply to all MID servers or particular ones?

(2) Did you include the domain in the username of the credential being used?

I'm not familiar yet with Service Mapping as I was trained for ServiceWatch but maybe this gives you some ideas:

(3) Is a specific MID server set on the Discovery Schedule used to discover your web server?

(4) Do you have a configured failover cluster for your MID Servers? If so, the first one with the lowest order will be used.

Kind regards,

Stijn

[tim_sewell]

Hi Stijn,

Thanks for the reply.  

1. The credential for the web server, in the Prod domain, applies to the Mid Server from the Prod domain.   The same is true for the Test domain credential and Mid Server.
2. Yes, the domain is included in the credentials.
3. Yes, the Prod domain Mid Server is assigned to the discovery schedule that contains the Web server.
4. No, I haven't configured failover clustering.

Tim

[Stijn Verhulst3]

Hi Tim,

I'm sorry but I'll have to dissapoint you in this one, have no ideas left...

[jonathanjacobcp · Accepted solution]

Hi Tim,

See the following KB article on hi:

ServiceNow Customer Service System

Improving MID Server selection algorithm

Problem

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Service Mapping creates discovery requests that contain the IP address of the entry point, the probe and the MID Server. Service Mapping then writes them in the ECC Queue table of CMDB (ecc_queue).

In Geneva patch 1-4, Service Mapping selects MID Servers for discovery requests using only IP ranges. If a MID Server does not have a defined IP range, Service Mapping treats it as suitable for any IP range and therefore can assign any discovery request to it. In a situation where there is a MID Server with the IP range matching the discovery request and a MID Server with no defined IP range, Service Mapping may select the MID Server with no defined IP range.

Symptoms

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Service Mapping may not discover the CI from the entry point.

Imperfect algorithm for MID Server selection in Service Mapping.

Resolution

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The algorithm of selecting MID Servers for discovery requests is improved in Service Mapping starting with Geneva Patch 5. We recommend that customers using earlier versions install a business rule that improves MID Server selection.

The business rule changes the algorithm to the following:

• (Optional, needs to be configured) Service Mapping can assign discovery requests only to MID Servers configured to work with Service Mapping
• Service Mapping uses only MID Servers with defined IP ranges
• If there are any entry points with IP address that does not match any defined IP ranges in MID Servers, Service Mapping assigns the discovery request for this entry point to the default MID Server
• If there is an entry point with no IP address (using hostname, such as http://www.google.com), Service Mapping assigns the discovery request for this entry point to the default MID Server

As a result, Service Mapping cannot randomly assign requests to MID Servers with no defined IP range.To install and configure this business rule, perform the following steps:

1. Install the business rule by importing the MIDBusinessRule.xml file attached to this KB article.
   
   
2. To use only MID Servers configured to work with Service Mapping:a. Navigate to the System Property table and click New.b. In the Name field, enter sa.service_mapping.use_capabilities.c. From the Type list, select true|false.d. In the Value field, enter true.e. Click Submit.
3. To select a MID Server as the default MID Server for Service Mapping:

a. Navigate to the System Property table and click New.

b. In the Name field, enter mid.server.sm_default.

c. From the Type list, select string.

d. In the Value field, enter the name of the MID Server to use as the default.

e. Click Submit.

For more information about business rules, see Business Rules.