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Understand the pros and cons of the IBM PowerVM

IBM's enterprise virtualization product, PowerVM, offers a host of benefits, but it also comes with challenges that admins should familiarize themselves with prior to implementation.

IBM's PowerVM offers a secure and scalable virtualization environment that enables IT administrators to consolidate workloads and better utilize server resources, while reducing administrative overhead and overall costs. Despite this, PowerVM comes with certain challenges, such as hardware compatibility issues and lack of support.

The IBM PowerVM is an enterprise-grade virtualization product created by IBM to run AIX, IBM i and Linux applications on IBM Power Systems. IMB's PowerVM enables admins to decrease cost, bolster system security and flexibility. Conversely, PowerVM relies on IBM's Power Systems hardware, so admins considering PowerVM should be wary of vendor lock-in.

An introduction to IBM's PowerVM

PowerVM is a combination of hardware, firmware and software components that provide a foundation for virtualizing CPU, storage and network resources. At the heart of PowerVM is the Power hypervisor, which is built into the Power Systems' firmware.

The Power hypervisor uses features in the Power processor to provide an abstraction layer between physical hardware resources and LPARs. The partitions are self-contained operating environments similar to VMs supported by other hypervisors. The Power hypervisor also enforces partition integrity, controls processor dispatching and monitors the service process.

LPARs provide a structure for creating independent server systems that run virtual workloads. A Power Systems server can support up to 1,000 LPARs, each running the AIX, IBM i or Linux OS. Admins can assign processor, memory and I/O device resources to each LPAR and dynamically reconfigure resources. PowerVM also supports a feature called Virtual I/O Server (VIOS), which makes it possible to share physical storage and network resources across multiple LPARs.

Key features in PowerVM

In addition, PowerVM supports Micro-Partitioning technology for allocating fractions of processors to LPARs. In this way, admins can distribute the processing capacity of one or more physical CPUs across one or more LPARs, resulting in improved resource utilization. Another important feature is Active Memory Sharing, which is an advanced memory virtualization technology that enables multiple LPARs to share a common pool of physical memory, adding to PowerVM's flexibility.

PowerVM also comes with several management tools such as the Hardware Management Console, a virtual appliance for configuring and controlling multiple PowerVM systems. Another tool is the Integrated Virtualization Manager, which is a VIOS extension for managing local PowerVM systems. Admins can also install the NovaLink software interface on PowerVM servers to carry out scalable cloud management and workload deployments. Plus, admins can use the PowerVP performance monitoring tool to access real-time information about virtualized workloads.

In addition, PowerVM enables admins to perform remote restarts on LPARs, suspend and resume LPAR operations, and migrate active or inactive LPARs from one system to another. PowerVM also includes virtual network adapters and Peripheral Component Interconnect Express extensions that enable multiple LPARs to share PCIe devices.

With PowerVM, IBM is specifically targeting enterprises already invested in Power Systems or that plan to purchase them in the near future to run their virtual workloads. PowerVM also represents an additional incentive for those considering a Power Systems purchase.

Because PowerVM is already integrated into the Power Systems platform, admins don't have to implement additional hardware or software. Admins need only enable one of three editions: PowerVM Standard; PowerVM Enterprise; or the IBM PowerVM, Linux Edition. Most Power servers support all PowerVM features; however, customers should contact IBM directly to verify whether a specific server supports every feature.

The pros and cons of PowerVM

PowerVM offers Power server admins a number of advantages, such as seamless integration into the Power Systems platform that delivers a highly secure environment to protect workload integrity and isolation. For example, the Power processor includes features specific to PowerVM such as Secure Boot, which uses digital signatures to perform hardware-protected verifications of firmware components.

In addition, PowerVM comes with PowerSC, a suite of components that includes Trusted Boot, Trusted Firewall and Trusted Logging. Plus, the Power hypervisor ensures that LPARs trying to access resources have the proper permissions to do so.

To use PowerVM exclusively, admins must lock themselves into all Power Systems equipment for their server virtualization needs.

PowerVM also provides a number of features that increase flexibility, such as Live Partition Mobility. This feature enables admins to move LPARs between servers to better utilize resources and support load balancing, while also providing a maintenance window that doesn't require downtime. PowerVM also makes it possible to dynamically allocate resources to applications as admins require, making it easier to address changing business requirements and fluctuating workloads.

To increase flexibility even further, IBM offers Capacity on Demand for Power Systems and PowerVM, a program that provides consumption-based pricing based on processor and memory usage. In addition, admins can scale their systems up or out without incurring performance penalties. PowerVM also makes it possible to consolidate workloads onto fewer servers, helping to reduce administrative overhead and better utilize hardware resources, all of which can lead to lower costs.

However, PowerVM brings with it several challenges. To begin with, IBM limits PowerVM to Power Systems hardware only. Although this is an advantage in terms of integration, it means that admins with servers from different vendors must purchase and manage different hypervisors for their virtual servers. To use PowerVM exclusively, admins must lock themselves into all Power Systems equipment for their server virtualization needs. At the same time, PowerVM doesn't support the Windows OS, again forcing admins to contend with multiple hypervisors and the licensing that goes with them.

Another challenge is that PowerVM isn't as widely implemented as other hypervisors, which might make it more difficult for admins to receive community support and feedback when required. In addition, some admins have found PowerVM to be somewhat difficult to deploy and much of its documentation outdated, which might leave admins wondering whether the product has the attention it deserves.

Despite these challenges, admins already committed to Power Systems could realize a number of important benefits, assuming their workloads can conform to PowerVM's OS limitations. PowerVM is directly incorporated into the Power Systems platform and brings with it the platform's integrated security, characteristics that go a long way in making PowerVM worth serious consideration for enterprise workloads.

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PowerVM now offers the possibility to share seamlessly CPU and memory resources within a pool of physical servers, with "Power Systems Private Cloud". Balancing computing power between servers is immediate. With this feature, cost optimization with pay-for-use pricing can also be implemented to drastically reduce CAPEX.

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