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Java Middleware & Systems Management

Physical Enterprise vs Logical Inventory

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A recent chat with a colleague reminded me today how important it is to clearly distinguish between what’s in your enterprise and what’s in your inventory. There doesn’t exist an RHQ dictionary yet, so until then, the following entries will have to do:

  • Enterprise – refers to all the physical machines connected by wires and power cords, installed in the racks in your data center, or plugged into the wall under your feet
  • Inventory – refers to the list of logical “resources” discovered by your RHQ infrastructure via some plugin

When you fire up the web console and login, you need to keep in mind that what you’re viewing is an abstracted layer. The inventory represents the information your RHQ plugins collected and sent back up to the server. So when you want to make a change, you have to decide whether you mean to make that change on the physical or logical level.

Logical Changes

For instance, if you just want to suppress the information that RHQ discovered (likely because it found and auto-imported much more than you need to manage/monitor right now), then your inventory – not your enterprise – is what you want to change. From the resource browser, regardless of whether you’re looking at the platforms, servers, or services tab, there is an “uninventory” button at the bottom.

Clicking it will tell RHQ to remove all information it knows about it (and all of its child resources) from its datastore. You’re effectively telling RHQ that you don’t want to manage this resource anymore. As a consequence, you will also lose any and all audit trails for that resource (and its children). Audit items could be anything from the results of operations you performed against it to the list of alerts that fired because the resource met some trigger condition. Don’t forget, audit items also include the entire set of configuration changes you’ve made to these resources since they’ve been in inventory, etc.

Physical Changes

On the other hand, sometimes you actually want to make a change to your physical enterprise, whether it be adding some new user to an existing Postgres database, or uninstalling an old enterprise/web application archive (ear/war) from a JBoss Application Server. In both cases, you want to go to the inventory tab of the parent of the resource you want to manipulate.

To delete an item from your physical enterprise, simply select one of the children resources from the tabular set and click “delete”. This sends a request down to the agent managing that resource and performs the necessary operations required to remove that item from your enterprise. This, in turn, also removes the logical resource from your inventory, but that’s really just a convenience because RHQ knows that if the delete succeeds, the resource no longer exists, so there’s nothing left to manage/monitor about it.

Adding a new item to your enterprise is just as simple. At the bottom of the table you’ll see a combobox labeled “Create New”. It will be populated with all of the resource types the RHQ plugin managing this parent resource knows how to physically create in your enterprise. Select one of them, click the button labeled “Add”, and follow the various steps on the subsequent pages.

One last reminder…

I can’t emphasize enough how important it is to keep these two concepts separate. One deals with adding / removing meta-information from the RHQ datastore; another is basically a primitive form of provisioning. If you accidentally deleted a physical entity when you only meant to uninventory its logical resource, don’t bother asking for help on any forum because there’s nothing that can be done. The product did what you asked it to do; your data is gone. But that’s OK because you religiously keep backups…right?


Written by josephmarques

May 7, 2008 at 10:10 pm

Posted in rhq

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