NovaLink is an exciting new virtualization management paradigm for PowerVM systems and allows for dramatic scale improvements for PowerVM based PowerVC environments. For more information on NovaLink and its benefits, see this blog post.
Leveraging the NovaLink architecture, PowerVC is able to significantly increase its scaling for PowerVM based systems. In an existing HMC managed environment, PowerVC can manage up to 30 hosts and up to 3000 virtual machines. In a NovaLink based environment, PowerVC can manage up to 200 hosts and 5000 virtual machines. Don’t worry though, you can use PowerVC to manage your new NovaLink systems while still managing your HMC managed systems.
To help explain the drastic scaling increase, let’s take a look at the architecture.
PowerVC NovaLink Architecture
PowerVC is built with OpenStack technology. One of the key components of the set of ‘host’ processes, such as nova-compute, neutron (networking) and ceilometer (statistics). Each host that is managed by PowerVC runs an independent set of these processes. In the diagram below, we see how PowerVC manages PowerVM Systems through the HMC. The HMC acts as a central management controller for sets of hardware. Given that the HMC is a closed appliance, this requires PowerVC to run the various compute processes on the PowerVC system directly. This increases the CPU and memory requirements on the PowerVC system, and limits scalability.
Another limitation is that when PowerVC manages through an HMC, it can only manage up to 500 virtual machines (LPARs) per HMC. An HMC that is not in use by PowerVC can scale higher, but due to monitoring and other ongoing processes it is tuned for 500 VMs when managed via PowerVC. That means if you want to take advantage of PowerVC at a higher scale, you would need multiple HMCs.
The NovaLink architecture changes the virtualization management point for PowerVC. With NovaLink, a thin ‘management’ virtual machine exists on the system. You can see the thin NovaLink partition denoted in the diagram below as ‘NVL’.
In the previous picture, we see that the architecture between PowerVC and a PowerVM system is dramatically simplified. The compute processes now run directly on the NovaLink thin virtual machine. This allows PowerVC to dramatically scale out the number of hosts that it can manage via this one-to-one link. It also reduces the load on an administrator’s HMC, allowing them to connect significantly more systems to a given HMC than they would otherwise.
On top of this, the NovaLink code is tuned directly for PowerVC & OpenStack use. This increased efficiency allows PowerVC to scale a single system to 1,000 virtual machines – double the current 500 VMs per system limitation that exists today. More importantly, it is aligned with the capabilities of the PowerVM platform itself.
Note: Co-management (HMC and NovaLink) support is currently a Technology Preview in HMC V8.840.0 and should not yet be used in a production environment. However, full support is coming very soon.
PowerVC NovaLink User Experience
While NovaLink’s architecture provides a very exciting foundation, the user experience modifications for PowerVC and NovaLink are decidedly boring. But that is by design.
It is our intent to provide a unified PowerVM experience. Whether you choose to have PowerVC manage through NovaLink (to take advantage of the scale and speed) or via the traditional HMC path, PowerVC provides you with a consistent experience.
As you can see, the experience within the interface is quite similar. In the image below, the home page looks identical, even though PowerVC is managing NovaLink systems. However, you should note the dramatic increase in hosts!
There are some areas where changes are evident in the UI. The obvious one is the Host Registration panel. While host registration for an HMC managed system remains unchanged, there is a new path for NovaLink host registration. Administrators provide the IP Address and credentials of the NovaLink VM, which PowerVC uses to register the system. This panel is similar to the panel used for PowerKVM system registration today.
Beyond this, there are very few other differences. The Host panel doesn’t show which HMC PowerVC is managing through (because it manages through NovaLink).
On top of this, to ensure a unified experience, we made sure that a single PowerVC can mix its management types. This means that a single PowerVC can manage some systems through an HMC, and others through NovaLink:
As you can see, the same HMC can be used for PowerVC traditional management, or NovaLink management. However, if a system has NovaLink installed, PowerVC must be pointed to the NovaLink on the system. We believe that this mixed mode provides a good path for our existing customers that want to start taking advantage of NovaLink without too much disruption.
Summary
NovaLink provides significant advantages for PowerVM users that want to scale up their environments. It is highly concurrent, highly scalable and can reduce infrastructure complexity. At the same time, the existing PowerVC experience is preserved enabling administrators to take advantage of these benefits quickly.
If you have questions about this exciting new technology, be sure to add a comment here, on our PowerVC LinkedIn, Facebook, or Twitter pages!. We look forward to hearing from you!