Virtualization on the plant floor
Joel Conover, Paul Hodge, Grant Le Sueur, Anthony Baker, Jim Tessler
Virtualization lifecycle considerations
This new approach can help keep some older platforms operating longer.
Most industrial process users seek to maximize the length of time they can stay on a particular control system platform for two reasons: increase ROI (return on investment) and reduce the amount of disruption to operations. Virtualization is a key technology that can assist in reducing the frequency of hardware refreshes, the cost of each refresh, and the impact to process operations when a refresh occurs, each of which accomplishes the goal of increasing ROI and mitigating operation disruptions.
When considering how virtualization can improve operations, users should consider the lifecycle implications of several layers. These include:
- Physical hardware
- Hypervisor (VMware, Hyper-V, etc.)
- Virtual hardware
- Virtualization drivers
- Operating system, and
Virtualization provides abstraction or separation of the operating system and application layers from the physical hardware. This reduces the dependencies that operating systems and applications have on hardware, and gives users improved choices for determining which supplier or platform will best meet their performance, reliability, and support goals. However, users need to be aware that there is a new dependency between the hypervisor and the hardware. Therefore, it is important to consider the compatibility between the hypervisor and the chosen hardware and how long that hardware combination will be supported.
This is a small software layer that runs the virtual machines, which can have a different lifecycle from other layers. Users need to take into account its lifecycle and corresponding support from the application vendor, particularly the frequency with which the hypervisor needs to be patched or upgraded. This is because, unlike a normal operating system that impacts only one application, taking a hypervisor down for maintenance may impact multiple operating systems. The ability to complete these updates in a way that is nondisruptive to operations is also important, and the ideal solution provides continued application execution during updates.
All major hypervisor manufacturers allow for continued application execution during upgrading and patching; however, users should check to ensure that these extended features are supported by the application vendors. Without this capability, maintenance windows will need to be found to patch or upgrade the hypervisor when necessary.
Virtual hardware is a software-emulated hardware layer that sits between the hypervisor and the operating systems used to run the applications. It emulates a motherboard with particular graphics, USB, sound, and other capabilities. Depending on the hypervisor supplier, this layer can have a separate release and support cycle. This is important as virtual hardware touches the operating system and applications inside the virtual machine. Extended stability in this layer can bring about simplified qualification of operating system/application solutions and reduced retesting.
Think of virtual drivers as regular drivers for virtual hardware instead of physical hardware. Because these drivers touch the operating system and application layers, the frequency of change and stability in the drivers is an important consideration.
Virtualization can extend the life of certain operating systems, and applications that depend on them, by allowing them to run on hardware that otherwise would not provide support. New hardware that supports Windows XP, for example, is very difficult to source. Yet it can be run virtually on new physical hardware as long as the hypervisor vendor supports Windows XP. An additional benefit of virtualization comes from not having to re-install the operating system when upgrading the physical hardware. But keep in mind that, in general, an operating system vendor’s physical or virtual support policy is the same. So, running a virtualized operating system does not allow for longer periods of support.
Similar to the operating system layer, running virtualized applications can provide additional flexibility by allowing them to run on hardware normally unsupported by the application vendor. However, there are additional considerations:
- In most cases virtualized applications will not change the duration that a given application is supported.
- The application vendor needs to have flexibility in support policy to allow the hypervisor to run on multiple hardware platforms.
- While a vendor may support multiple hardware platforms, it may still have standardized offerings to aid in support and project deployment, among other areas.
To obtain the new types of flexibility that virtualization provides, additional layers are required and the lifecycle implications of these layers need to be understood. With the correct support from their application vendors, users can achieve better ROI from their process control system lifecycle while reducing the amount of disruption to operations.
Paul Hodge is virtualization product manager for Honeywell Process Solutions.