IT Operations Management (ITOM)

What is the difference between active vs. passive, agent vs. agentless and how can they help you?

What is the difference between active vs. passive, agent vs. agentless and how can they help you?


Why does it matter if I have an agent, agentless or passive discovery?  Is there really a benefit to having each of these?  Why is this so important?  Most stakeholders today need information on what makes up their environment and how it relates, are dependent on completely or partially manual methods.  These methods are error prone, provide stale data and are hugely incomplete.  Manual methods cannot scale to address the complexity or frequency of change issues associated with any large modern enterprise.  What is required to address the issue of complexity and frequency of change is automated discovery of what makes up the environment and automated mapping of these elements and their relationships.


HP Universal Discovery (UD) provides you with active, passive, agent and agentless discovery capabilities.   Which is the best discovery method?  The answer is dependent on your needs and end-goals.  Agentless discovery has no need to deploy or maintain an agent on each serve, nor is there a need to maintain a presence on discovered devices, resulting in a minimal footprint.  There is less change management and build process concerns.  As a result, the code is not being deployed to machines and no changes to builds are occurring, so less overhead is required for the deployment.  UD’s agentless discovery also leverages available access points (protocols) to get desired information.  The main benefit of going the agentless route is there are less political hurdles to leap in order to get the system deployed.   The agentless discovery is also non-intrusive, meaning agents do not reside on the local machines and deployment commonly does not require administrative access to machines.


UD’s agent discovery provides a “Deep-Dive” of inventory, in terms of depth of data.  For example it might be difficult to record a daily account of what software is being used on a machine without an agent in place.  It is argued by agent driven vendors that it makes more sense to deploy to a machine that only periodically connects to the network if you wish to maintain an accurate inventory.  Network bandwidth will improve with agent discovery, but will depend on the strength of your network connections and remote locations, but it is argued that it is more network-friendly to have an agent transmitting audit results over the network.  An agent-based discovery also allows for a “call home” functionality to facilitate inventory of users for non-durable connections.  In layman’s terms, if a server, laptop, workstation, etc. is disconnected from the network and connects back in, the agent will issue a call to retrieve all the data it has collected while disconnected from the network.  UD allows the organization to choose the best method of discovery per the specific needs and constraints of each management zone.


Which is the best discovery technology?  Again, this is answered by determining what is best for your company.  HP’s active-based discovery allows for a balanced scheduling, frequent (creates more noise) or infrequent (stale data).  This enablement allows for a rich, customizable configuration mapping for a deep discovery, but requires credentials.  Passive discovery, also known as Just-in-Time discovery, performs a continuous, shallow discovery with no noise.  Administration and management of the integration is being done in UD itself and is also credential-less.  UD integrates with HP Real User Monitoring (RUM) to act as Passive Discovery Probe, to continuously sense network traffic in real time allowing for the capture non-durable connections as well as durable connections.  The UD passive discovery probe is plugged into a data-center router/switch and captures information by being connected to SPAN (or mirror) port.  Combining the capabilities of both Passive and Active discovery to achieve Real-time detailed discovery. 


IT organizations have complete control over the timing, frequency, scope, and downtime windows in the discovery process.  This flexibility gives you the power to accurately discover what exists in your IT environment and map how it relates to other IT elements which support your business-critical services.  HP Universal Discovery provides the basis for understanding the services that IT delivers—from the physical layer of the data center all the way to the business process layer.  HP Universal Discovery provides you with the tools you need to discover what you have and the business service dependencies within your IT environment.


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Follow our blog series: Unified Discovery:

  • How can Management Zones, Native Agent Packaging, and the New Shell Protocol changed the way you discover?
  • Can the Discovery Trouble-Shooter get you out of a jam?
  • How to put ROI and discovery together…
  • What’s new in Content Pack 11?


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