Hey CMDB experts - What is the benefit of creating VM instances?

[Suggy]

We know that ServiceNow creates one entry in VM instance and anohter entry for its host in Server table when discovering servers in cloud.

My question is - what is the use of discovering VM instances? Technically is a duplicate and redundant record for me, unless you say its not 🙂

Please share your feedback if know the rationale behind it/use cases of VM instances.

[SteveMacWWT]

@Suggy This is an easy thing to be confused on, it took me a long time to come up with a good explanation for it. 

The easiest way to understand this is to think of a Windows Server is referencing the Operating System that is running on Hardware. (Yes, the server includes details about the hardware. This really is a legacy usage of configuration items in relation to everything ran on hardware. That paradigm is not unique to ServiceNow; it can be seen in most other CMDBs as well.) In regards this to discussion, focus on the Server in terms of the OS only. 

There are capabilities and attributes of VM instances which are relevant to that object which hardware servers do not have. Instead of overpacking the Windows or Linux server classes with new attributes, ServiceNow took the opportunity to break from that legacy model for these new (at the time) types of Servers. One of the key benefits of having VM CIs is that if you have the integration set up with your VM management tool, it can be configured so that when a VM is moved to another VM host, that can be automatically updated in the CMDB. For example if you have multiple data centers and the VMs are configured to automatically move depending on traffic, availability, etc., you will be able to see which VMs are running in which DC. 

In short, for a Server running in a VM, the VM CI represents the pseudo-hardware that the OS is running on.

You can also see the effects of this perspective when it comes to CIs and Assets. By default, an Asset is not created  for a VM. 

With all that said - if you do not have a use for VM CIs, then by all means, do not track them. As with anything in the CMDB you should only track what is beneficial to your company. 

[chrisberg]

Tracking and storing are I would say 2 different things.  I would not mess with the details coming into the Instance records, it has multipe uses.  It links the VM environment to the Physical device.  It can set which VM server and/or which vm cluster is hosting the VM along with all the resources that VM uses(storage clusters, VM networking, ETC.)  It is used if you ever bring in the VM Migration tools.  You have to seperate what is "Hardware Details"(IE what the actual virtual is windows, linux and all their Hardware inventory) to what is VM details (IE host to vm environment is running that virtual)

[Suggy]

@chrisberg @SteveMacWWT Thanks a lot for your inputs. But to my understanding the usage/use cases are limited.

I checked with few infra team members and they were least bothered. They said the info available in ServiceNow is very limited, they use the vCenter utility to manage and view everything. So felt like this data in ServiceNow us not useful to anyone ;0

[chrisberg · Accepted solution]

Just some final thoughts from me.    You are correct and most clients use vCenter for management.  But ServiceNow goes farther than management.  It links things together that vCenter doesnt, and if that vm instance is not there you disconnect the line between the Computer record and the VCenter system is running in.  If ever you plan on doing any event monitoring, Service Mappings, these come in as a requirement, cause and effect reporting type of scenario. For day to day stuff yes, it can be ignored, and I would just do that Ignore the records.  If in the future the other products serviceNow provides needs it in the middle, then you have that detail that ServiceNow can use.