If there are any CMDB experts, pls help in understanding CI relationships wrt upstream & downstream?

[Suggy]

1. OOB the relationship between the SQL DB instance and Server is

Database RUNS ON::RUNS  Linux server

and the form view is like this:

But one of our infrastructure team person saying its the other way around, ie the relationship should be

Database  RUNS::RUNS ON  Linux server

and says the map should be like this where Linux server is the Upstream and Database is the Downstream because, when the upsteam CI (Linux) is down, then the Downstream CI (Database) will also be down.

For this happen, I need to create a new entry cmdb_rel_type table with RUNS::RUNS ON, and only then I can see the map as shown above.

Also if I did this way, the Upstream and Downstream also shows properly in the form view.

So its really making sense what that person is saying.

Then why ServiceNow has built it other way round? If you see the 2nd image, If I use oob relationships, linux server is showing under Downstream relationship.

Confused!!!

If you know.have clarity on this, pleasee share the details.

[AndersBGS]

Hi @Suggy ,

From my perspective it will always be the MySQL instance running on the Linux server. Always see infrastructure/CIs as the lowest level of CIs. Furthermore.

If my answer has helped with your question, please mark my answer as accepted solution and give a thumb up.

Best regards

Anders

[Suggy]

Hi @AndersBGS Could you please tell the rationale behid this statement "Always see infrastructure/CIs as the lowest level of CIs"

[SteveMacWWT]

When reading the relationships you need to do so using the portion of the relationship closest to the perspective you are looking at, and ignore the other. Start with one object, use the part of the relationship (RUNS ON::RUNS) that is closest to that object, and then the other object. 

So in the case of Database RUNS ON::RUNS Linux server it should be read as "Database RUNS ON Linux server", or you can read it backwards "Linux server RUNS Database". 

NOTE: You can create the same effective relationship by either:

Go to the Database, select "RUNS ON::RUNS" and find the Linux server,

OR

Go to the Linux Server, select "RUNS::RUNS ON" and find the Database.

As far as whether the relationship shows in Upstream / Downstream, I believe it depends on how you added the relationship - did you do it from the Database or from the Linux server? If there were an attribute on relations that indicated what is upstream vs what is downstream that could be made visible. Unfortunately that is not there. 

Steve

[Suggy]

Hi @SteveMacWWT 

Reg your question "As far as whether the relationship shows in Upstream / Downstream, I believe it depends on how you added the relationship - did you do it from the Database or from the Linux server? "

From either of the CI you add, it doesnt make any change, it will be the same behavior.