Configuration Item relationship directions

[Colin13]

Currently working on the CMDB and CSDM and questions are being raised about relationship directions, using a piece of a equipment in a rack, which direction should the relationship go, should it be that the rack is the parent of the equipment, 

e.g

an application service would then be a child of the IP router if that was the last object

I have seen examples using both directions and hoping that people can offer their comments and experience on this as I can't seem to find a definitive answer

thanks

Colin

[Ted N1]

I would take a very pragmatic approach when it comes to hardware (and software). In which order do you need to assemble/mount/install the CI's? Thinking about the order should give advice on parent/child relationship. Then choosing the relationship type is another story but CI Class Manager can most likely give guidance... BR Ted

[Barry Kant · Accepted solution]

Hi Colin, 

I think there are 2 ways to look at this, and that can be seen in CSDM as well. 

From a Business side it is modelled from an impact point of view, meaning the impact upstream the relations. As CI 'I am supporting this Application Service --> upstream'

From the Technical side it is modelled from a supportability point of view. As Technical Service Offering 'I am managing/supporting this CI --> downstream'

The datacenters are to be compared with the Technical side I would say, as it is not seen as Business. 

About CI Relation types: I would use an exclusive relationship type, and limit that one from the impact analyses logic (which is not ootb). 

Example in the visualization:

if an Incident is raised on this router the impact analyses show that the Rack and the Computer Room are impacted. Where impact wise it would be the other way around. I there is a power outage in the rack the router will be impact. 

In my opinion it is a different purpose where impact analyses might not be needed. 

Cheers,

Barry

[Colin13]

Thanks Barry, that helps my thinking From looking in the relationship table my above visualisation should show that the rack is the parent of the router, which from my understanding would mean that the router would be impacted if there was a problem with the rack (impact to the dependant), but from my understanding of your answer the impact is to the parent rather than the child? Thanks again Colin

[Barry Kant]

Hi Colin,

in the ITSM processes 

• Incident
• Change

there are Refresh Impacted Service UI actions. Those are defined to look upstream the relations (so from Child to Parent) to understand the Potential Impact to Services. The result is that it lists all relations (multi-level) where the parent(s) is/are in the cmdb_ci_service table (or an extend from this table).

The other logic to look downstream would be if you fill a Service Offering in the Incident, that you would like to find a Configuration Item that is related downstream of the Service Offering. 

So:

Impact --> Upstream

Support/Members/Containments --> Downstream.

Cheers,

Barry