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
What this presentation is not
 In anyway comprehensive
Basic Terms and Common Things
Virtualization Basics
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
 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
 Limiting factor that determines how many virtual
systems can be started
 Cannot guarantee more resources than physically
 PowerVM – Entitlement
 VMWare - Reservation
Virtualization Basics
 Limit
 Maximum amount of resources that a virtual system can
 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
 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
 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
 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
 Contention for physical resources
 PowerVM – Involuntary Context Switches
 VMWare – CPU Ready
Performance Measurement
 Measurements from inside the virtual system
 PowerVM
Entitlement vs. Virtual Utilization
Performance Measurement
 Measurements from inside the virtual system
 VMware
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

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