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

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