Showing results for 
Show  only  | Search instead for 
Did you mean: 

Virtual Vs. Physical: Enterprise Synthetic Agents

The idea for this article was the need we
have for a good overview of the Pro's and
Con's of having Virtual agents over Physical agent devices. So far I did not find such an page elsewhere.

I can come up with several, and obvious, benefits and
penalties, but I wanted to have it as true and complete as possible.
This so it can be used with business case discussions. Hence this article is always open for improvements.

Virtual Vs. Physical: Enterprise Synthetic Agents

obvious benefit of virtual systems is perhaps the cost aspect, you do
not need to buy and maintain hardware for every agent, and replace it
after so many years. The speed and virtual limitless amount of new
deployments, worldwide, are some of the other. Increasing system
resources is much easier as well.

The restrictions however lay in
the dependency of a virtualization server platform on site, which limits
the flexibility in choosing the workplace to monitor from, and perhaps
the dependency of other teams to maintain your agent's availability.
Plus there is the question of how representative are the measurements
from a virtual DC system to that of the actual End User Experience,
measured by a standard workplace system in office LAN environment. Which
may draw different measurements, than a virtual machine (VM) in a
steady data-center environment.

Here are from the perspective of Virtual Agents over Physical agents, the following Pro's an Con's I could think of with some help from the community:

Maintenance and Infrastructure

Virtual Pros:

  • Lower hardware costs (same OS license requirements apply), no additional hardware per agent
  • No hardware parts that can break down, and need to be replaced (except in host environment)
    Host environment is
    usually much more redundant, and break-down of one or even a few hardware components
    usually cause no or very minimal (in order of seconds) downtime, whereas in case of
    hardware usually the environment is down up until the breakdown part is
    replaced, and, in case of a hard drive, the contents is restored.
  • No hardware life-cycle replacement (except on host), nor depreciation
  • Faster deployment, more in minutes than in days
  • Availability;
    when a physical device is broken, it takes hours to days, fix or
    replace. A virtual device can be replaced within a short time.
  • System resources as CPU, memory and disk-space can be added easy, and almost instantly
  • Worldwide deployment without export/import restrictions, customs, or local supplier or support dependencies
  • VMs can be transported physically. No physical shipping/logistics involved for sending/returning units.
  • The
    right/standard VM can be build centrally, and deployed with greater
    ease. Physical systems have to be imaged, and likely need extra
    installation work after imaging.
  • Deployment from inside a
    data-center can be seen as a pro in certain situations, bringing
    monitoring close to the platforms to be measured, without bringing extra
    hardware into the DC. If policy's allow bringing in desktops at all.

Virtual Cons:

  • Requires Virtual Hosting environment (e.g. VMware/ESX)
  • Placement
    restricted to the availability/position of a hosting platform or
    server. Often this is a datacenter/dataroom, with it's own network
    access. Although in situations that can also be considered a pro.
  • A
    physical device can virtually be placed anywhere, and there where the
    real users are (LAN). (For VM's this would mean placing a host in such
  • A virtual agent (in a DC) is not as representative as
    a standardized workplace machine in terms as simulating end user
    experience. The hardware specs are not aligned.
    Images for virtual pcs are slightly different from the images of the
    physical pcs. That’s because that there
    is other hardware underneath the agents.
  • Deploying VMs requires
    base-lining well the performance of the VMs together with physical
    workplaces, and record and anticipate on the differences.
  • Overload on the VM platform could impact the VM's performance.
  • The need of specific hardware, such as graphical interfaces, requires physical units.
  • The ability to upgrade Windows
    and sometimes other software involved may be limited. Plus limitations might exist in upgrading
    host environments, so in virtual world you may also need to create
    the environment from scratch.

Physical Pro:

  • A clear physical agent pro, is the flexibility to place an agent in a
    hotspot when and where needed in case of need of need of ad-hoc
    measuring; Even installing software on an existing user desktop is an
  • You can use agents with different
    memory / CPU sized according to the actual state of the PCs in your firm.

There may also be differences in capacity, the amount of transactions
that can be run in a certain timeframe, before the system or the network
connection becomes saturated. But in both cases this can be addressed
by expansion, where a VM in general of course is easier to be expanded, but until certain limitations.


Virtual Pros:

  • Ease of remote control/accessibility.
  • No dependency on local staff, for physical control/management.
  • Power control through the host. No PDU/power(-over-IP) switches, or local staff required.
  • Remote (KVM) access through the host. No separate KVM (Keyboard/Video/Mouse) switches or over-IP solutions required.
  • When OS not reachable, or network port not functioning, a VM still can be reached through the host.

Virtual Cons:

  • Access required to hosting server/platform; To control the VM, the
    staff that manages the agents need to be able to have access to control
    the VM through the host; Modern virtual platforms should be able to
    manage the necessary access control; This involves an extra layer of
    security account management;
  • If for a reason access is not possible to the VMs host, there is adependency on other teams managing the VM infrastructure.
  • In
    case of major IS changes a simultaneous downtime or performance degrade of
    multiple environments is possible.


Virtual Pros:

  • The unit and it's console are automatically protected by the host
    platform; No one can walk in and just access the machine. Since the
    agent requires an unlocked screen to run it's tests, this imposes a
    security risk when the physical agent is placed in an open office space.
  • No physical vulnerability, no secured area or protective measures
    necessary, where a physical unit in an office space would be vulnerable
    to hardware tampering, like unplugging, powering off, removal of

Virtual Cons:

  • As stated before, the control of the VM depends on the (level of) access to the hosting platform.
  • A proper access control configuration is required, allowing the right personal control and access the VM.


Virtual Pros:

  • Perhaps the stability of the virtual platform and the (data center)
    network might be in favor of a virtual agent, in terms of a clean
    'network' for measurements.
  • The use of virtual agents is great
    for base-lining application performance measurements. However the
    biggest difference is in the:

Virtual Cons:

  • The measurement of virtual agents, may (or will) not be 100% representative for End User Experience Measuring, in
    relation to the use of physical agents that use company standardized
    hardware, that regular users utilize. Although nowadays there is a lot
    of variety in user hardware as well.
  • The use of virtual agents
    involves measuring and defining the baseline measurements in detail, and
    compare these with the results of the physical equivalents. This to
    determine if there are deviations between the two, that may need to be
    taken into account. These differences might be very small, but present.
  • Measurements right there where the host spots are, is easier with a physical device that can be placed anywhere when needed.
  • Since images share
    resources of the host environment, measurements represent not only the
    application being monitored, but also the load of the host environment.

There are benefits to follow a heterogeneous approach, and inter mix
physical with virtual agents, in both datacenters as user lan area's.
Measuring on several locations and areas, give both insight in user
experience, as pure application performance.

I'm very interested in anybody's additions, improvements and adjustments!

I would like to give special thanks to @Antoon Rodoe and @Yuriy Look for their valuated review and input while coming to this Article.

Happy Measuring!




Thanks for the contribution! It's posts like these that will greatly improve the forum.


Thank you for this article. It's articles such as this that greatly improve our community,