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New PowerVM NovaLink Feature Enhances OpenStack Integration


PowerVM’s new NovaLink feature for POWER8 servers provides a direct connection between PowerVM-based servers and OpenStack managers. Previously, virtual machine (VM) deployment on PowerVM-based servers required PowerVC to act as an interface between PowerVM and an OpenStack manager. PowerVC can continue to be used as a simplified OpenStack manager and has been enhanced to interface with NovaLink.

OpenStack Compute Services

OpenStack is an open source-based cloud management solution used to deploy, manage and monitor VMs. The computing service module of OpenStack is called Nova. Nova provides infrastructure as a service (IaaS) functionality and has two components: Nova-controller and Nova-compute. Nova-controller runs on the OpenStack manager and coordinates VM create/mange requests. Nova-compute interacts directly with the system hypervisors to create/manage VMs. Each physical server requires its own Nova-compute service, which serves as a control point for the VMs running on that server. For PowerVM-based servers, the Nova-compute service was previously provided by PowerVC. The new PowerVM NovaLink feature provides Nova-compute services directly on the server where the VMs are running.

Nova Provisioning With the PowerKVM Hypervisor

Let’s start by reviewing the original design for OpenStack Nova-compute integration with the hypervisor. OpenStack provides native Nova-compute integration for Kernel-based Virtual Machine (KVM), VMware, Hyper-V, Xen and a few other hypervisors. This native support allows OpenStack Nova-controller VM create/manage requests to be passed directly to the Nova-compute service running on the hypervisor. IBM Power Systems servers running the PowerKVM hypervisor have this same, native support for Nova-compute built into the hypervisor, as shown in Figure 1.

Each physical server has its own Nova-compute service. This design parallels the deployment of KVM on Intel-based servers. Note that PowerKVM environments do not support the use of a hardware management console (HMC).

Nova Provisioning for PowerVM With PowerVC and HMC

For hypervisors that do not have native OpenStack support, it is necessary to provide an interface between the OpenStack Nova-controller and the hypervisor. Prior to the introduction of NovaLink, PowerVM did not have direct OpenStack Nova-compute support and required a separate interface to OpenStack. PowerVC served as this interface. For each physical server, there is a Nova-compute service that runs on PowerVC, as shown in Figure 2.

These individualized Nova-compute instances act as the control point for the VMs running on their corresponding servers. OpenStack Nova-controller VM create/manage commands are sent to corresponding Nova-compute services on PowerVC. These requests are then forwarded from PowerVC through an HMC and down to the physical server. The requirement to have a separate Nova-compute interface instance for each physical server limited PowerVC to the management of approximately 30 physical servers.

Introducing PowerVM NovaLink

In an effort to simplify the deployment of OpenStack with PowerVM, IBM recently introduced the PowerVM NovaLink feature. Use of NovaLink also improves PowerVC performance and scalability by removing the Nova-compute workload from PowerVC. NovaLink places the Nova-compute function directly onto the PowerVM based server, as shown in Figure 3.

NovaLink runs in a dedicated Linux LPAR, one per physical server. This LPAR provides the Nova-compute functionality. OpenStack VM create/manage requests now flow directly to NovaLink, which then communicates with the hypervisor. OpenStack managers interact with NovaLink through using representational state transfer (REST) APIs. A special command line interface (CLI) for communication from NovaLink to PowerVM is also provided. NovaLink supports the following OpenStack services:

  • Nova (compute)
  • Neutron (networking)
  • Ceilometer (monitoring/usage)

NovaLink operates as a single image per server. Redundant NovaLink servers cannot be configured. If a problem is detected, the hypervisor will automatically restart the NovaLink VM. Note that NovaLink is only used with PowerVM-based environments. NovaLink is not required for PowerKVM servers because PowerKVM has native Nova-compute support as previously discussed. PowerVM NovaLink currently runs on an Ubuntu Linux VM. Other Linux distributions are under consideration by IBM. NovaLink runs as a standard LPAR with I/O support provided by Virtual I/O Server (VIOS). NovaLink is included with PowerVM at no additional charge and is supported on POWER8 servers. When implementing NovaLink, PowerVC can continue to be used as an OpenStack manager. In this configuration, the Nova-compute services will no longer be present on PowerVC. PowerVC V1.3.0 provides support for interaction with NovaLink-based PowerVM implementations. When PowerVC is used with NovaLink, the number of physical servers that can be managed by PowerVC increases from 30 to 200. Also, PowerVC now supports virtual machine placement with multiple shared-processor pools.

Using NovaLink and HMC-managed Servers

When using NovaLink with HMC-managed servers, either the NovaLink or an HMC is the master used to control the VMs on the server (master mode), but not both. There is a command that can be run on the HMC to switch master mode on and off. The term “co-management” is used when running NovaLink on servers that are connected to an HMC. Co-management support is currently offered in preview mode on HMC V8.840.0. When NovaLink is operating as the master, the HMC can still be connected and used for server maintenance tasks like firmware updates, CoD resource management and problem reporting. When a PowerVM-based server is configured with NovaLink, the traditional HMC management environment is different. Partition profiles no longer exist on the HMC; they are all managed by OpenStack and NovaLink. Note that the HMC continues to be required for E870 and E880 servers.

Support Timing

NovaLink is included with PowerVM V2.2.4. NovaLink is initially supported only with the Integrated Virtualization Manager (IVM)-based servers running PowerVM. A preview version of NovaLink is available for non-production testing with HMC-managed servers. Full support for HMC-managed Power servers will become available at a later date.

A New Direction for PowerVM and OpenStack

NovaLink provides a simplified, direct link between OpenStack managers and the PowerVM virtualization environment. It is no longer necessary to have a PowerVC server acting as an intermediary interface between OpenStack and PowerVM. PowerVC continues to be available as OpenStack manager for PowerVM and PowerKVM environments.

Charlie Cler supports customers in a solutions-architect role at Forsythe Technology Inc. He can be reached at ccler@forsythe.com.




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