Derived from VMware Education Services ‘Virtual ... · Derived from VMware Education Services ‘Virtual Infrastructure’ See for course schedule

Derived from VMware Education Services ‘Virtual Infrastructure’See http://www.vmware.com/services/education.html for course schedule


Resource Management for ESX Server I

Russ HenmiTechnical Trainer

VMware, [email protected]


Objectives

To understand the mechanisms used automatically inside ESX Server to allocate and optimize resources


Systems for Optimizing Resource Use

Virtual Switch with Teamed NICs

Maximum Size

Virtual SMP

Virtual Machine Owner

Share Allocation

Share AllocationService console

Traffic Shaping

Share Allocation

Minimum SizeShare Allocation

Page SharingvmmemctlUse of VMkernel swap

Minimum RateMaximum RateProcessor AffinityShare Allocation

Load BalancingHyperthreadingVirtual

machine

Virtual Machine Administrator

VMkernel


VMkernel CPU Load BalancingSingle VCPU virtual machine runs on only one physical CPU at a timeDual VCPU virtual machine runs on two physical CPUs at a time, or noneVMkernel dynamically schedules virtual machines and Service Console

Every 20 milliseconds, VMkernel looks for virtual machines to migrateService Console always runs on CPU 0

CPU 0 CPU 1 CPU 2 CPU 3


HyperthreadingHyperthreading allows one Xeon or P4 to execute two threads simultaneously

Each physical CPU offers two logical CPUs (“LCPUs”)VMkernel will intelligently schedule VCPUs onto LCPUs

CPU-intensive VCPUs will run in different PCPUs


VMkernel Memory TechniquesAllow RAM over-commitment

VMkernel swap is reserved whenever a virtual machine's maximum RAM exceeds its minimum RAM

Economize on memoryTransparent Page Sharing allows pages with identical contents tobe stored only onceAlways active unless administratively disabled

Deallocate memory from one virtual machine for another Ballooning mechanism forces virtual machines to use their own paging areasActive when memory is scarce

Page virtual machine memory out to diskUse of VMkernel swap space is the last resort, performs poorly


Transparent Page SharingShare identical pages

Copy detection algorithmExample: more than 30% shared w/ idle Win2K virtual machines

No changes to guest OS required

Copy-on-write (“COW”)Read-only when sharedPrivate copies after write


vmmemctl: The Memory Control MechanismDeallocate memory from selected virtual machines when RAM is scarce

inflate balloon (driver demands

memory from guest OS)

guest is forced to page out;

VMkernelreclaims memory

guest may page in; ESX Server grants memorydeflate balloon

(driver relinquishes memory)

ample memory;balloon remains

uninflated


Virtual Machine Administrator ToolsYou can manage all virtual machines’resources through:

VMware Management Interface (MUI)Must log in as user root

VirtualCenter clientMust be a virtual machine administrator user

/proc/vmwareVMware Scripting API


How Virtual Machines Compete for ResourcesProportional-share system for relative resource management

Applied during resource contentionPrevents virtual machines from monopolizing resourcesGuarantees predictable resource shares

Change # Shares

Power on virtual machine

Power off virtual machine


CPU Resource Settings: Percentages and Shares

Minimum absolute percentageA percentage of a physical CPU reserved for this virtual machineThe VMkernel chooses which CPU, and may migrate

Maximum absolute percentageA cap on the consumption of CPU time by this virtual machine, as a proportion of a physical CPU

Range is 0-100% for uni virtual machinesRange is 0-200% for dual virtual machines

Because VCPUs in the same virtual machine are always co-scheduled

Proportional shares (relative)More shares means that this virtual machine will win competitions for CPU time more often


Managing Processor SchedulingProcessor Affinity

To LCPUs if hyperthreading is enabledTo PCPUs otherwise

If you specify lists of physical CPUs for each virtual CPU, there must be no overlapDo not try to force both virtual CPUs of an SMP virtual machine to the same physical CPU

MUI VirtualCenter


Memory Resource SettingsMaximum absolute size

Maximum memory that this virtual machine can use

Minimum absolute size

Guaranteed physical memory during contention

Proportional shares (relative)

In contention, virtual machines win in proportion to their proportion of the competing shares

Across entire system:Sum of all virtual machines’ (maximum -minimum) must be less than VMkernel swapSum of all virtual machines’ minimum RAM must be less than VMkernel RAM


Virtual Machine Memory Admission Control

Virtual machines power on only if:Minimum memory available (by default, half the memory size)Enough swap space to cover difference between max and min size


Viewing Memory Utilization

At least minimum memory size

At least maximum minus minimum memory size

For virtual machine being powered on:


Disk Bandwidth ManagementProportional shares per LUN


Controlling Network Bandwidth in ESX Server

Limits outbound network bandwidthHard limit: applies even when more bandwidth is available

Average rate, peak rate, burst size per virtual machine


Service Console CPU SharesThe service console uses by default:

2000 CPU shares8% guaranteed minimum CPU usage


Service Console Disk SharesShares for each physical disk used by the Service Console on an adapter shared with the VMkernel, if any


SummaryProportional Share Mechanism

Used to allocate CPU, Memory, Disk BandwidthTo govern CPU utilization

Allocate shares, specify minimum and maximum ratePossibility to use Virtual SMPRestrict virtual machines to physical CPUs

To govern memory allocationSpecify minimum and maximumBe sure to install VMware Tools (for the balloon driver)If over-commitment is desired, configure VMkernel swap

Not the same as Service Console swap space!


Questions?


PAC879: The Next Phase of Virtual Infrastructure: Introducing ESX Server 3.0 and VirtualCenter 2.0

PAC177: Distributed Availability Services ArchitecturePAC484: Consolidated Backup with ESX Server:

In-Depth ReviewPAC485: Managing Data Center Resources Using the

VirtualCenter Distributed Resource SchedulerPAC532: iSCSI and NAS in ESX Server 3

This presentation covers the current versions of our products. Details about

future releases of our products are available in select sessions at VMworld, including:

Documents

Derived from VMware Education Services ‘Virtual ... · Derived from VMware Education Services ‘Virtual Infrastructure’ See for course schedule