Manifests and dynamic server selection

You can use collectors, manifests, and selectors together to choose a server resource at run time for a project or step.
Three different data objects allow the system to dynamically choose servers:

The following example shows how to create and use a simple selector:

  1. Create a server resource named Mercury and associate it with an agent.
  2. Create a selector named Mercury. Set it to selects servers with BF_NAME = Mercury.
  3. Create a project named Lincoln. Assign the Mercury selector to it.

When you run the Lincoln project, the system selects the server resource named Mercury. If that server resource is not available, the project fails.

The following example shows how to set up dynamic server selection in a set of servers:

  1. Create a collector named RAMSIZE. Set it to collect the Built-in property MEM_TOTAL.
  2. Create server resources to associate with hosts. Set each one to use collector RAMSIZE.
    • Mercury, a host with 512 MB RAM
    • Mars, a host with 1 GB RAM
    • Jupiter, a host with 3 GB RAM
  3. Create a selector named BigRam. Set it to select a Standard Property, property=MEM_TOTAL, Operator=GE (Greater than or Equal), and Value=2048. MEM_TOTAL is expressed in MB. This selector selects only hosts that have 2 GB of RAM or more.
  4. Create a selector named SmallRam. Set it to select a Standard Property, property=MEM_TOTAL, Operator=GE (Greater than or Equal), and Value=256. This selector selects only hosts that have 256 MB of RAM or more.
  5. Create two projects:
    • HighMaint: set this project to use selector BigRam.
    • LowMaint: set this project to use selector SmallRam.

When you run HighMaint, the system chooses the server Jupiter, because it is the only one that meets the selector requirement of having at least 2 GB of RAM.

When you run LowMaint, the system chooses any of the three server resources that is available.

If you later add a server resource named Neptune for a host that has 2 GB RAM, then the next time project HighMaint runs, one of either Neptune or Jupiter is selected for the project. If Jupiter is down for some reason, then Neptune is selected. It is the only one left that fits the selector.


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