February 5, 2008 Virtualization Trends On IBM s System P Unraveling The Benefits In IBM s PowerVM

Transcription

1 Virtualization Trends On IBM s System P Unraveling The Benefits In IBM s PowerVM by Brad Day with Simon Yates and Rachel Batiancila EXECUTIVE SUMMARY IBM s PowerVM (formerly Advanced POWER Virtualization) technology has catalyzed the consolidation of server systems resources and a variety of applications workload types both AIXand Linux-led as virtualized on more powerful multi-core System p servers. Evolution of IBM s virtualization stack has improved dramatically from its early 2001 introduction of logical partitions on the first multicore POWER4-based systems to its current PowerVM virtualization stack. In 2007, IBM s refresh to POWER6 came fast and furious: debuted with high-end System P 570 (in May), followed by the P6-based JS22 blade (November), and sweeping through the System P 520 (entry) model and System P 550 (midrange) server (January 2008). Traction for PowerVM virtualization now accounts for 70% of its IT customer base showing to what extent IBM s virtualization stack has become a shortlist contender as a systems consolidation enabler. The November 2007 release of AIX 6 added two breakthrough features Live Partition Mobility and Live Application Mobility further cementing IBM s advanced virtualization advantages against its Unix competitors. QUESTIONS 1. What s the history behind the IBM virtualization stack? 2. What is the overall business value of the System p virtualization stack? 3. What role does the POWER Hypervisor play in the PowerVM? 4. How does the POWER Hypervisor integrate with PowerVM technologies? 5. What are the benefits of micro-partitioning and the shared-processor pool? 6. What are workload partition (WPAR) and Live Application Mobility? 7. What business problems are solved with PowerVM s new Live Partition Mobility? THE EVOLUTION TO ADVANCED VIRTUALIZATION Virtualization technology while relatively new in the x86 world has been a core capability in RISC Unix-based systems for years. Over the years, the core benefits achieved through advanced Unix virtualization have been focused on three drivers: creating a greater flexibility in how to change, move, and add system architecture resources, improving applications isolation and availability, and the speed Headquarters Forrester Research, Inc., 400 Technology Square, Cambridge, MA USA Tel: Fax:

2 2 in which to meet the changing requirements for systems resources and capacities -- whether as enablement in server consolidation projects, in mixed workload and test environments, and finally, in the consolidation of operating system images and/or applications workloads.. 1. What s the history behind the IBM virtualization stack? LPARs were the first step in IBM s virtualization strategy. With the release of AIX 5.1 and POWER4 technology almost eight years ago, IBM introduced logical partitions (LPARs) as a way to provide greater flexibility and better use of large systems. At this point, systems could run both AIX and Linux in separate partitions, starting with a minimum of one CPU, 1 GB of memory, and one Ethernet adapter. However, before the system administrator could move any resources between LPARs, he had to reboot the operating system. Dynamic LPARs added flexibility by eliminating reboots. With the introduction of AIX 5.2, dynamic logical partitions added more systems flexibility by allowing administrators to move CPU, I/O adapters, and memory dynamically without having to reboot the LPARs. This System p innovation was the result of combining firmware, the hypervisor, and AIX. It was a key breakthrough that allowed systems administrators to create, move, or delete systems and application workload resources all using virtual resources. APV moved beyond CPU and memory virtualization. APV, introduced in the AIX 5.3 operating system and the POWER5-based System p, made it possible to not just virtualize CPUs and memory, but share Ethernet adapters and virtually slice disk resources for provisioning to the end user. With APV, IBM System p could facilitate server consolidation, reduce costs, provide a whole new level of virtualized redundancy, and adjust and optimize all forms of systems resources and application workload capacities to quickly respond to changing business demands. Live partition migration allowed virtualized resources to move between machines. While single-system virtualization can greatly improve flexibility, some requirements demand a more comprehensive view across data center infrastructure. Even though IBM System p was designed with extreme high availability within a single-server complex, some scenarios required a change or stop to certain applications workloads, partitions, or entire server environments for a variety of planned maintenance procedures. Live partition migration allows an administrator to move a running, in-production application from one server to another without disruption. It can reduce planned downtime by dynamically moving applications from one server to another, respond to changing workloads and business requirements by moving workloads, and reduce energy consumption by allowing you to easily consolidate workloads and temporarily (or permanently) power down unused servers.

3 3 2. What is the overall business value of the System p virtualization stack? The operational expectation of any IT department is to respond to business demands. These demands can be simply the addition of new applications workloads or systems, required changes in the capacity of service-level standards, or the required response times inherent in the existing server systems. Non-virtualized IT deployments involve the detailed specification, sizing, and configuration of many individual systems elements, including servers, networks and switches, storage area networks (SANs), and storage. Selection and purchase of new hardware and the time taken to test, stage, and then deploy into production can be lengthy and costly. The advent of System p virtualization provides a more rapid and cost-effective response to the setup, optimization, and deployment of applications workloads and other systems resources. Specifically, PowerVM allows an IT organization to increase the overall use of its servers, lower management and administration costs by reducing the number of physical servers, lower power and cooling costs, and speed time to application deployment. 3. What role does the POWER Hypervisor play in PowerVM? The POWER Hypervisor is the foundation for virtualization on a System p server. It enables the hardware to be divided into multiple partitions and ensures strong isolation between them. Always active on the System p server, the POWER Hypervisor is responsible for dispatching the logical partition workload across the physical processors and delivers functions to other systems technologies like micro-partitions, virtual processors, a VLAN-compatible virtual switch, virtual SCSI adapters, and virtual consoles. In many ways, the POWER Hypervisor is the traffic cop for the physical server resources and the virtual resources: It enforces partition integrity by providing a security layer between the logical partitions; it provides an abstraction layer between the physical hardware resources and the logical partitions using them; it controls the dispatch of virtual processors to physical processors; it saves and restores all processor-state information during logical processor context switching; and it controls hardware I/O interruption management for logical partitions. 4. How does the POWER Hypervisor integrate with PowerVM technologies? The POWER Hypervisor allows you to define logical partitions. A logical partition is not constrained to physical processor boundaries and may allocate processor resources from a shared-processor pool. An LPAR that uses processor resources from the shared-processor pool is known as a micro-partition LPAR. With the POWER Hypervisor, it s possible to move system resources, physical processors, virtual processors, memory, and I/O slots between partitions without rebooting. Known as a dynamic LPAR, it s a core capability in improving System p hardware use in a virtualized environment. The POWER Hypervisor also controls functionality of:

4 4 Virtual Ethernet. The POWER Hypervisor implements the Ethernet transport mechanism, as well as an Ethernet switch that supports the VLAN capability. Virtual LAN allows for secure communication between logical partitions without the need for a physical I/O adapter or cabling. This ability to securely share Ethernet bandwidth across multiple partitions can significantly improve hardware utilization rates. Virtual SCSI. The POWER Hypervisor can provide the functionality for virtual SCSI, allowing secure communication between the partitions and a virtual I/O server that provides storage back-up devices. The combination of virtual SCSI and the virtual I/O server capabilities lets you share storage adapter bandwidth and divide single large disks into smaller segments. The adapter and disks can then be shared across multiple partitions, in turn increasing system use dramatically. Virtual I/O. The virtual I/O server is essentially an appliance server with which you can associate and share physical resources among a group of logical partitions. For virtual Ethernet, you can define shared Ethernet adapters on the virtual I/O server, bridging the network traffic from the virtual Ethernet networks out to physical Ethernet networks. The virtual I/O server technology facilitates the consolidation of both LAN and disk I/O resources and minimizes the number of physical adapters that are required, while still meeting all of the other functional requirements of the server. The virtual I/O server can run in either a dedicated processor partition or a micro-partition. 5. What are the benefits of micro-partitioning and the shared-processor pool? Micro-partitioning is the ability to divide computing power of a physical processor into fractions of a processing unit and share them among multiple logical partitions, allowing the increased overall use of CPU resources. Better granularity of CPU allocation in a logical partition means more efficient use of the available processing power. The virtualization of physical processors in POWER systems introduces an abstraction layer that is implemented with the hardware microcode. From the operating systems perspective, a virtual processor is the same as a physical processor. The key benefit of partitioning hardware is that it allows any operating system to run on POWER server technology with few or no changes. In fact, the operating system can be enhanced to exploit shared-processor pools by voluntarily relinquishing CPU cycles to the hardware when these cycles are not required. Micro-partitioning allows multiple partitions to share one physical processor. These shared-processor partitions are allocated processor resources from a single pool of physical POWER processors, referred to as the shared-processor pool. The amount of processor capacity that is allocated to a micro-partition called its entitled capacity may range from 10% of a physical processor to 100% of the physical shared-processor pool. The physical shared-processor pool can have from one physical processor up to the total installed processor capacity of the system. Any changes to the entitled capacity of a micro-partition can be as granular as 1% of a physical processor.

5 5 New to POWER6-based systems, there is now support for multiple shared-processor pools. This allows the system administrator to create a set of micro-partitions to control the processor capacity that they consume from the physical shared-processor pool. Each shared-processor pool has an associated entitled pool capacity, which is consumed by the set of micro-partitions in that sharedprocessor pool. They are guaranteed to receive their entitled capacity, and unused processor cycles can be harvested and distributed to eligible micro-partitions within the same shared-processor pool. When the micro-partitions in a shared-processor pool are heavily loaded, they can consume additional processor capacity from outside their shared-processor pool up to a defined maximum known as a maximum pool capacity. In a shared logical partition, there is no fixed relationship between the virtual processors and physical processors. The POWER Hypervisor can use any physical processor in the shared-processor pool when it schedules the virtual processor. The POWER Hypervisor, coupled with the shared-processor pool, can adjust and match the best combination of physical resources (memory and CPU) to address the wide variety of workload requirements of the virtual micro-partitions being serviced at any one time. 6. What are workload partition (WPAR) and Live Application Mobility? With the release of AIX 6.1 in November 2007, IBM introduced a new virtualization capability called workload partition (WPAR). WPAR is a software partitioning solution provided by the operating system for partitioning one AIX operating system across multiple environments. Each environment, called a workload partition, can host full application workloads and isolate them from applications executing in other LPARs. The application in the WPAR thinks that it s being executed in its own AIX instance. WPARs can be created within an AIX 6 LPAR and should be considered a boundary around a set of AIX processes. In AIX 6, a new term AIX global environment has been introduced and refers to the part of the AIX operating system that hosts workload partitions. It should be noted, however, that creating a WPAR within an LPAR doesn t restrict the use of hosting AIX instances. It s possible to log in to the global environment, launch a program, and perform the same actions on an AIX instance that doesn t host WPARs. To use workload partition effectively, it s important to understand the significance of a global environment in an LPAR. As mentioned, workload partitions are created with standard AIX6 instances, and the global environment is the part of the AIX6 instance that doesn t belong to any workload partition. The global environment is similar to the operating system environment of an earlier version of AIX. The system administrator must log in to the global environment to create, activate, and manage workload partitions. The global environment owns all the physical resources of the LPAR network adapters, disk adapters, disks, processors, and memory and allocates CPU and memory resources to the workload partitions and provides them access to the network and storage devices. Additionally, performance monitoring takes place from the global environment.

6 6 Accompanying the benefit of workload partitions is Live Application Mobility, a feature that allows for the planned migration of WPAR workloads from one system to another without interrupting the application. You could also use this technology to perform a planned firmware installation on the server; the actual workloads themselves don t have to be aware of the WPAR relocation. The relocation of a WPAR consists of moving its executable code from one LPAR to another while keeping the application data on the same storage device. It s therefore mandatory that these storage devices be accessible from both the source and target LPARs hosting the WPAR. The benefits of using WPARs are extensive. WPARs can: Reduce application downtime. If an application is not part of a cluster of servers providing continuous availability, WPARs can reduce the application s downtime. For instance, during server physical maintenance, you can use Live Application Mobility to temporarily move the applications that are running on that server with no blackout period. Increase flexibility in resource-constrained application environments. WPAR technology can also help when an application needs to be started in a one-off, on-demand way. This might apply, for example, in testing, where resources are too scarce to keep multiple applications running when not in use. Using WPARs, many applications can be defined on a server, but not activated. Activation of the workload partition executing each of these applications can be performed only when needed for a test. Simplify server administration. WPAR technology also has tremendous benefit in simplifying the administration and handling of the entire software stack. With virtualization and partitioning technology, you can host multiple applications within partitions of a physical server, but you need to maintain one operating system instance for each application. WPAR technology lets you share an AIX instance among multiple applications while still running each application within its own environment, providing isolation between applications. In this case, the more applications that are consolidated with one AIX instance, the less the system administrator has to perform OS fix applications, backups, migrations, and other OS maintenance tasks. Serve as safety nets in the event of a failure. WPAR technology can be integrated as one element of business continuity and disaster recovery. The checkpointing feature of WPAR allows you to capture a snapshot of an executing application without having to instrument the code. The application checkpoint image is then saved to a file that can be used later to resume the execution of the application. Combined with the application backup data, the WPAR checkpoint can provide alternative disaster or failure recovery for applications that don t use more expensive server clustering and failover solutions.

7 7 7. What business problems are solved with PowerVM s Live Partition Mobility? While single-system virtualization greatly improves the flexibility of an IT solution, customers service requirements often demand a more comprehensive view of the infrastructure. In many instances, applications are distributed across multiple systems, ensuring isolation, optimizing global systems resources, and adapting the infrastructure to new workloads. However, one of the most time-consuming tasks is the actual transfer, or re-hosting, of an application workload from one system to another. There are a myriad of reasons for migration, which include: Resource balancing. In this case, one server doesn t have enough resources for the workload, while another server does. New system deployment. Sometimes a workload running on an existing system must be migrated to a new, more powerful system, such as one with substantial price/performance advantages. Availability requirements. When a system requires maintenance, its hosted applications keep running and can be migrated to another system. Without a way to easily migrate a partition, all of these activities require careful planning and highly skilled and expensive people resources, and often cause significant system operations disruption and downtime. In some cases, an SLA may be so strict that planned outage is not tolerated. IBM s Live Partition Mobility is a new POWER6-based technology that attempts to address these application workload or system resource migration concerns. It s the newest feature and differentiated part of the PowerVM, and allows you to migrate running AIX and Linux partitions, as well as their hosted applications, from one server to another without disruption to either the infrastructure services organization or the affected users. Migration can take just a few seconds, during which time complete system transactional integrity is maintained. Because of its virtualized state, the migration can transfer the entire system stack, including processor state memory, attached virtual devices, and connected users. Live Partition Mobility can be automated and incorporated into the system management tools and scripts. Support for multiple concurrent migrations allows changes, moves, and additions to happen very quickly. The Hardware Management Console (HMC) offers an easy-to-use wizard for single-partition and point-to-point migration. Partition migration can be made either when the partition is powered off called inactive migration or when the partition is providing service called active migration. During an active migration, there is no disruption of systems operation or user service. For example, a partition hosting a live production DBMS with normal user activities can be migrated to a second system with no loss of data, connectivity, or performance. Essentially, a logical partition may be migrated between two POWER6-based systems, provided the destination system has the adequate overall systems resources to host the partition. The benefits are extensive; Live Partition Mobility:

8 8 Can improve service-level agreements (SLAs). It allows you to proactively move running partitions and applications from one server to another. Handles peak workloads better. Should a key application s resource requirements peak unexpectedly to a point where there is contention for the server resources, you might move the application to a larger server, or alternatively, move the less critical partitions to different servers and use the freed-up systems resources to absorb the workload peak. Improves consolidation opportunities. Live Partition Mobility becomes a key enabler for more efficient server consolidation, providing an easy path to move applications from individual standalone smaller servers to a more powerful and larger consolidation server target system. Potentially lowers power and cooling costs. If you have workloads that have widely fluctuating resource requirements over time for example, with a peak at the end of the month or end of the quarter you can use Live Partition Mobility to run these applications on a single consolidated server during the off-peak period, allowing you to power off unused servers and move only the affected workloads to their own, more adequately configured servers just prior to the peak time period. This saves energy required to power the machines and to keep them cool. Forrester Research, Inc. (Nasdaq: FORR) is an independent technology and market research company that provides pragmatic and forward-thinking advice to global leaders in business and technology. For more than 24 years, Forrester has been making leaders successful every day through its proprietary research, consulting, events, and peer-to-peer executive programs. For more information, visit , Forrester Research, Inc. All rights reserved. Forrester, Forrester Wave, RoleView, Technographics, TechRadar, and Total Economic Impact are trademarks of Forrester Research, Inc. All other trademarks are the property of their respective companies. Forrester clients may make one attributed copy or slide of each figure contained herein. Additional reproduction is strictly prohibited. For additional reproduction rights and usage information, go to Information is based on best available resources. Opinions reflect judgment at the time and are subject to change. To purchase reprints of this document, please resourcecenter@forrester.com