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Comparing Virtualization Platforms. PowerVM and VMware. What this presentation is. Basic Terms that can be used to discuss multiple forms of virtualization Concepts common to virtualization platforms that make planning easier
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Comparing Virtualization Platforms PowerVM and VMware
What this presentation is • Basic Terms that can be used to discuss multiple forms of virtualization • Concepts common to virtualization platforms that make planning easier • Notable differences between virtualization platforms that should be understood when planning • IMHO
What this presentation is not • In anyway comprehensive
Virtualization Basics Basic Terms and Common Things
Virtualization Basics • Physical Capacity • The amount of resources physically present • Virtual systems have little or no visibility
Virtualization Basics • Hypervisor • Abstraction layer between physical hardware and virtual systems • PowerVM – Firmware • VMWare - Software
Virtualization Basics • Accessible Capacity • Amount of resource that a virtual system can potentially have access to • Also the amount of resource that a virtual system thinks it has access to • PowerVM – Virtual CPUs • VMWare – Virtual CPUs
Virtualization Basics • Guaranteed Capacity • Amount of resource that a virtual system can have no matter what other demands are placed on the physical resources • Limiting factor that determines how many virtual systems can be started • Cannot guarantee more resources than physically present • PowerVM – Entitlement • VMWare - Reservation
Virtualization Basics • Limit • Maximum amount of resources that a virtual system can access • PowerVM – Cap – Tied to guaranteed capacity • VMWare - Limit – Not tied to guaranteed capacity
Virtualization Basics • Priority • How resources are divided when demand is greater than physical capacity • Only affects access to accessible resources above the amount guaranteed • PowerVM – Priority Weight • VMWare – Shares
Virtualization Basics • Mobility • Ability to move virtual systems from one physical hardware device to another with no disruption in service to the virtual system • Independence from physical hardware • PowerVM – Live Partition Mobility (LPM) • VMWare - vMotion
Cluster vs. Host • VMWare – Cluster centric focus • PowerVM – Host centric focus
CPU • Scalability • Number of vCPUs supported for a single virtual system • Performance rating of physical hardware • Coscheduling and Processor Folding • Configuration flexibility • Adding/removing resources • Hot Add/Hot Plug • Threading Differences
Memory • Committed vs. Not Committed • VMWare • Transparent Page Sharing • Balloon Driver • PowerVM • Active Memory Sharing • Active Memory Expansion
Storage - Space • VMWare – Cluster/Pool Storage • Storage allocations are presented to all of the hosts within a cluster and formatted with a proprietary file • Virtual system is a set of files within the filesystem controlled by the hypervisor. • PowerVM – Direct Storage • Storage allocations are presented to VIO servers which then proxy them to the virtual system (vscsi) or storage allocations are presented directly to the virtual system (npiv) • Virtual system directly formats and manages storage
Storage - Throughput • Multipathing support • Quality of Service (Storage IO Control)
Priority vs. Guarantee • Reverse order of application • PowerVM – Guarantee applied first then Priority Weight • VMWare – Shares applied first then Reservations
Performance Measurement • CPU • Contention for physical resources • PowerVM – Involuntary Context Switches • VMWare – CPU Ready
Performance Measurement • CPU • Measurements from inside the virtual system • PowerVM • PURR • Entitlement vs. Virtual Utilization
Performance Measurement • CPU • Measurements from inside the virtual system • VMware • Skew • Run Queue in single vCPU virtual systems
Performance Measurement • Memory • Tracking memory allocation and usage by virtual systems • PowerVM – N/A? • VMWare • Actively used • Shared • Balloon/vmmemctl • Swap • Consumed • Overhead
Performance Measurement • IO Measurement • PowerVM – NPIV configurations have a measurement gap at the the physical HBA
Performance Measurement • Cluster Vs. Host Measurement • PowerVM – Virtual systems collect their own performance information • VMWare – Hypervisor collects performance information