About Ownership Options
When configuring Cloud Hub or TCG connections, you have the opportunity to designate how ownership of the hosts you add through this connection are owned. It's important to understand these options if you need to use merged hosts (hosts monitored by more than one monitoring application, for example Cloud Hub and Nagios together. Hosts can have only one owner application, but can be updated by more than one. Services by contrast can only be updated by one application.
Hosts can be set to not care if a new application merging with it takes ownership. If so, any new application that tries to merge with it will become the owner unless that new application also has that setting, in which case the app that created the host keeps it.
So, what does this mean for selecting the Ownership option? Well, when connecting to a GroundWork server with an application you can decide to do two things with any new hosts you add:
- Keep them yours (Always Take Ownership)
- Allow the next app to take ownership and not try to get it back (Always Defer Ownership)
If you're not sure yet what you will need, choose Leave Ownership if Already Owned. This will not take over any ownership on merge, but you can still grab it with an application set to Always Take Ownership.
For merging your app's hosts with hosts which already exist with the same name (and have owners), the owner may have chosen either of the above option. You need to decide what to do in each case. You can:
- Always take ownership. Choose Always Take Ownership.
- Take ownership only if the previous owner defers. Choose Leave Ownership if Already Owned.
- Never take ownership, effectively leaving the ownership unchanged no matter what. Choose Always Defer Ownership.
This is useful if you want to create the hosts automatically with one application, but have another application ultimately own them. Set the first app to Always Defer, and the second to Always Take.
For example, if you use Cloud Hub on VMware VMs in combination with GDMA and Nagios, you may encounter a timing issue. Cloud Hub is very fast in creating the hosts, but you will probably want to have Nagios control the hosts and be able to delete them. In this case, just set the Cloud Hub to Always Defer Ownership, and Nagios to Always Take Ownership (that's its default), and that's what will happen.
It's possible to have two (or more) applications all updating the same host. If two (or more) of them are set to Always Take Ownership, the ownership will flip back and forth between them. Avoid this by using the Leave Ownership if Already Owned for all but the one application you want to "take" the hosts.