VS5ICM_M10_ResourceMonitoring

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Resource Management and Monitoring

Module 10

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You Are Here

Course Introduction

Introduction to Virtualization

Virtual Machines

VMware vCenter Server

Configure and Manage Virtual Networks

Configure and Manage Virtual Storage

Managing Virtual Machines

Data Protection

Access & Authentication Control

Resource Management and Monitoring

High Availability

Scalability

Patch Management

Installing vSphere Components

VMware vSphere: Install, Configure, Manage – Revision A

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Importance

Although the VMkernel works proactively to avoid resource contention, maximizing performance requires both analysis and ongoing monitoring.


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Module Lessons

Lesson 1: Virtual CPU and Memory Concepts

Lesson 2: Resource Controls

Lesson 3: Resource Pools

Lesson 4: Monitoring Resource Usage

Lesson 5: Using Alarms


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Lesson 1:Virtual CPU and Memory Concepts


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Learner Objectives

After this lesson, you should be able to do the following:

Discuss CPU and memory concepts in a virtualized environment.

Describe what over commitment of a resource means.

Identify additional technologies that improve memory utilization.

Describe how virtual SMP works and how hyperthreading is used by the VMkernel.


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Memory Virtualization Basics


guest OS virtual memory

guest OS physical memory

ESXi hostphysical memory

application

operating system

VMware® ESXi™ host

virtual machineThere are 3 layers of memory in VMware vSphere®.

Guest OS virtual memory is presented to applications by the operating system.

Guest OS physical memory is presented to the virtual machine by the VMkernel.

Host physical memory managed by the VMkernel provides a contiguous, addressable memory space that will be used by the virtual machine.

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Virtual Machine Memory Overcommitment


Allow RAM overcommitment

A virtual machine swap file (.vswp) is created when a virtual machine’s maximum RAM allocation exceeds its minimum RAM allocation

Virtual machines power on only if:

Minimum memory available, that is overhead memory

Swap file size equals the difference between allocated and reserved memory

VM 1256 MB.vswp

VM 2256 MB.vswp

VM 3256 MB.vswp

On On On Off

256MB 256MB 256MB 256MB

allocated memory = 512 MB

reserved memory = 256 MB

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Memory Reclamation Techniques


Economize use of physical memory pages

Transparent Page Sharing allows pages with identical contents to be stored only once

Deallocate memory from one virtual machine for another

Ballooning mechanism, active when memory is scarce, forces virtual machines to use their own paging areas

Memory compression

Attempts to reclaim some memory performance when memory contention is high

Page virtual machine memory out to disk

Use of VMkernel swap space is the last resort, performs poorly

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Memory Compression


Guest OS physical memory

A 4K B

2K

2K

= memory compression cache

Memory pages are compressed to 2KB and stored in a per-VM compression cache.

Memory pages that are candidates for swap to disk are targeted for compression.

Decompressing a compressed page in memory is faster than performing disk I/O operations.

Compression only takes place when there is contention for physical memory resources.

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Virtual SMP


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Hyperthreading

Hyperthreading enables a core to execute two threads, or sets of instructions, at the same time.

To enable hyperthreading:

1. Verify that system supports hyperthreading.

2. Enable hyperthreading in the system BIOS.

3. Ensure that hyperthreading for the VMware ESX®/ESXi host is turned on.


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CPU Load Balancing


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Review of Learner Objectives

You should be able to do the following:

Discuss CPU and memory concepts in a virtualized environment.

Describe what over commitment of a resource means.

Identify additional technologies that improve memory utilization.

Describe how virtual SMP works and how hyperthreading is used by the VMkernel.


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Lesson 2:Resource Controls


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Learner Objectives


Describe the resources that can be optimized on virtual machines.

Assign share values for CPU, memory, and disk resources.

Establish CPU, memory, and disk reservations and limits.

Describe how virtual machines compete for resources.


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Resource Contention

Since virtual machines simultaneously use the resources of a physical server, they should know how to respond when virtual machines are competing for resources.

For proper resource management, vSphere has mechanisms to do the following:

• Enable less, more, or an equal amount of access to a defined resource

• Prevent a virtual machine from consuming large amounts of a resource

• Allow a virtual machine, whose performance is not adequate or requires a certain amount of a resource to run properly, to have a defined amount of resource


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Shares, Limits, and Reservations


available capacity

0 MHz/MB

limit

Shares are usedto compete in

this range.

reservation

A virtual machine willpower on only if its reservation

can be guaranteed.

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How Virtual Machines Compete for Resources


Number of shares

Change number of shares

Power on virtual machine

Power off virtual machine

VM A

1000

VM B

1000

VM C

1000

VM A

1000

VM B

3000

VM C

1000

VM A

1000

VM B

3000

VM C

1000

VM D

1000

VM A

1000

VM B

3000

VM D

1000

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Managed by VMkernelConfigured by virtual machine creator

Adjustable by administrator

CPU cycles

• Hyperthreading• Load balancing• NUMA

• VMware vSphere Virtual Symmetric Multiprocessing

• Limit• Reservation• Share allocation

RAM

• Transparent page sharing

• vmmemctl• Memory compression• VMkernel swap files

for virtual machines

• Available memory

• Limit• Reservation• Share allocation

Disk bandwidth

• Virtual machine file location

• Multipathing

Network bandwidth

• NIC teaming • Traffic shaping

Systems for Optimizing Virtual Machine Resource Use


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Describe the resources that can be optimized on virtual machines.

Assign share values for CPU, memory, and disk resources.

Establish CPU, memory, and disk reservations and limits.

Describe how virtual machines compete for resources.


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Lesson 3:Resource Pools


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Learner Objectives


Describe resource allocation settings for CPU and memory.

Create a resource pool.

Set resource pool attributes.

Describe expandable reservations.


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What Is a Resource Pool?

A resource pool is a logical abstraction for hierarchically managing CPU and memory resources.

It is used on standalone hosts or clusters enabled for vSphere Distributed Resource Scheduler (DRS).

It provides resources for virtual machines and child pools.


resource pools

rootresource

pool

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Why Use Resource Pools?

Using resource pools can result in these benefits:

Flexible hierarchical organization

Isolation between pools and sharing within pools

Access control and delegation

Separation of resources from hardware

Management of sets of virtual machines running a multitier service


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Resource Pool Attributes

Resource pool attributes:

Shares:

• Low, Normal, High, Custom

Reservations, in MHz and MB

Limits (in MHz and MB):

• Unlimited access, by default (up to maximum amount of resource accessible)

Expandable reservation?

• Yes – Virtual machines and subpools can draw from this pool’s parent.

• No – Virtual machines and subpools can draw only from this pool, even if its parent has free resources.


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Resource Pool Scenario

Company X’s IT department has two internal customers:

The finance department supplies two-thirds of the budget.

The engineering department supplies one-third of the budget.

Each internal customer has both production and test/dev virtual machines.

We must cap the resource consumption of the test/dev virtual machines.


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Resource Pool Example


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Resource Pools Example: CPU Shares


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Resource Pools Example: CPU Contention


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Expandable Reservation

Borrowing resources occurs recursively from the ancestors of the current resource pool.

Expandable Reservation option must be enabled.

This option offers more flexibility but less protection.

Expanded reservations are not released until the virtual machine that caused the expansion is shut down or its reservation is reduced.


Retail pool

reservation: 3,000MHz

expandable reservation: Yes

Root resource pool

total CPU: 10,200MHz

total memory: 3,000MB

eCommerce Apps pool

eCommerce Web pool

reservation:1,000MHz

expandable? No


expandable? Yes

An expandable reservation might allow a rogueapplication to claim all unreserved capacity.

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Example of Expandable Reservation (1)

eCommerce resource pools reserve 2,200MHz of the 3,000MHz that the Retail pool has reserved.

Power on virtual machines in the eCommerce Web pool.

With Expandable Reservation disabled on the eCommerce Web pool, VM3 cannot be started with a reservation of 500MHz.

Lower the virtual machine reservation.

Enable Expandable Reservation.

Increase the eCommerce Web pool’s reservation.


Retail pool


expandable reservation: No

VM1

R=400

VM2

R=300

VM3

R=500

Root resource pool

Total CPU: 10,200MHz

Total memory: 3,000 MB

eCommerce Apps pool

eCommerce Web pool


expandable? No


expandable? Yes

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Example of Expandable Reservation (2)

Enable Expandable Reservation on the eCommerce Web pool.

The system considers the resources available in the child resource pool and its direct parent resource pool.

The virtual machine’s reservation is charged against the reservation for eCommerce Web.

eCommerce Web’s reservation is charged against the reservation for Retail.


Retail pool reservation: 3,000MHz

expandable reservation: Yes

Root resource pool

Total CPU: 10,000MHz Total memory: 3,000MB

VM4R=500

VM5R=500

VM6R=500

VM1R=400

VM2R=300

VM7R=500

VM3R=500

**200MHz used by Retail**

**full reservation used**

eCommerce Apps pool

eCommerce Web pool


expandable? Yes


expandable? Yes

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Admission Control for CPU and Memory Reservations


Power on a virtual machine. Create a new subpoolwith its own reservation.

Increase a pool’sreservation.

Expandablereservation?

Can this poolsatisfy reservation?

No

Yes – Go to parent pool.

Succeed

FailNo

Yes

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Resource Pool Summary Tab

Click the resource pool’s Summary tab in the Hosts and Clusters inventory view.


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Resource Allocation Tab

Click the resource pool’s Resource Allocation tab.


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Scheduling Changes to Resource Settings


Schedule a task to change the resource settings of a

resource pool or a virtual machine.

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Lab 15

In this lab, you will create and use resource pools on an ESXi host.

1. Create CPU contention.

2. Create a resource pool named Fin-Test.

3. Create a resource pool named Fin-Prod.

4. Verify resource pool functionality.


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Describe resource allocation settings for CPU and memory.

Create a resource pool.

Set resource pool attributes.

Describe expandable reservations.


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Lesson 4:Monitoring Resource Usage


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Learner Objectives


Monitor a virtual machine’s resource usage:

• CPU

• Memory

• Disk

• Network bandwidth


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Performance-Tuning Methodology

Assess performance.

Use appropriate monitoring tools.

Record a numerical benchmark before changes.

Identify the limiting resource.

Make more resources available.

Allocate more.

Reduce competition.

Log your changes.

Benchmark again.


Do not make casual changes to production systems.

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Guest Operating System Monitoring Tools


Task ManagerIometer

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Using Perfmon to Monitor Virtual Machine Resources


The Perfmon DLL in VMware Tools provides virtual machine processor and memory objects to access host statistics

inside a virtual machine.

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VMware vCenter Server Performance Charts

The Performance tab displays two kinds of charts for hosts and virtual machines:

Overview charts:

• Display the most common metrics for an object

Advanced charts:

• Display data counters not shown in the overview charts


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Interpreting Data from the Tools

VMware vCenter Server™ monitoring tools and guest operating system monitoring tools provide different points of view.


Task Manager inguest operating system

CPU Usagechart for host

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Is a Virtual Machine CPU-Constrained?

If CPU usage is continuously high, the virtual machine is constrained by CPU.

But the host might have enough CPU for other virtual machines to run.


Check the virtual machine’s CPU usage.

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Are Virtual Machines CPU-Constrained?

Multiple virtual machines are constrained by CPU if:

There is high CPU use in the guest operating system

There are relatively high CPU ready values for the virtual machines


CPU Ready graph of several virtual machinesTask Manager of several operating systems

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Is a Virtual Machine Memory-Constrained?

Check the virtual machine’s ballooning activity: If ballooning activity is high, this might not be a problem if all virtual machines

have sufficient memory. If ballooning activity is high and the guest operating system is swapping, then

the virtual machine is constrained for memory.


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Is the Host Memory-Constrained?

If there is active host-level swapping, then host memory is overcommitted.


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Monitoring Active Memory of a Virtual Machine

Monitor for increases in active memory on the host:

Host active memory refers to active physical memory used by virtual machines and the VMkernel.

If amount of active memory is high, this could lead to virtual machines that are memory-constrained.


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Are Virtual Machines Disk-Constrained?

Disk-intensive applications can saturate the storage or the path.

If you suspect that a virtual machine is constrained by disk access:

Measure the throughput and latency between the virtual machine and storage.

Use the advanced performance charts to monitor:

• Read rate and write rate

• Read latency and write latency


Inventory object Chart option Storage type

Host Datastore FC, iSCSI, NFS

Host Storage adapter FC

Host Storage path FC, iSCSI

Virtual machine Datastore FC, iSCSI, NFS

Virtual machine Virtual disk FC, iSCSI, NFS

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Monitoring Disk Latency

To determine disk performance problems, monitor two disk latency data counters:

Kernel command latency:

• The average time spent in the VMkernel per SCSI command.

• High numbers (greater than 2–3ms) represent either an overworked array or an overworked host.

Physical device command latency:

• The average time the physical device takes to complete a SCSI command.

• High numbers (greater than 15–20ms) represent a slow or overworked array.


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Are Virtual Machines Network-Constrained?

Network-intensive applications often bottleneck on path segments outside the ESX/ESXi host:

Example: WAN links between server and client

If you suspect that a virtual machine is constrained by the network:

Confirm that VMware Tools is installed.

• Enhanced network drivers are available.

Measure the effective bandwidth between the virtual machine and its peer system.

Check for dropped receive packets and dropped transmit packets.


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Lab 16

In this lab, you will see how CPU workload is reflected by system monitoring tools.

1. Use vCenter Server to monitor CPU utilization.

2. Undo changes made to your virtual machines.


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Monitor a virtual machine’s resource usage:

• CPU

• Memory

• Disk

• Network bandwidth


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Lesson 5:Using Alarms


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Learner Objectives


Create alarms with condition-based triggers.

Create alarms with event-based triggers.

View and acknowledge triggered alarms.


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What Is an Alarm?

An alarm is a notification that occurs in response to selected events or conditions that occur with an object in the inventory.

Default alarms exist for various inventory objects:

Many default alarms for hosts and virtual machines

You can create custom alarms for a wide range of inventory objects:

Virtual machines, hosts, clusters, datacenters, datastores, networks, distributed switches, and distributed port groups


Default datacenter

alarms (partial list)

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Alarm Settings

To create an alarm, right-click the inventory object and select Alarm > Add Alarm.


Alarm types for:

Virtual machinesHosts

ClustersDatacentersDatastoresNetworks

Distributed switchesDistributed virtual port groups

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Alarm Triggers

An alarm requires a trigger. Types of triggers:

Condition or state trigger – Monitors the current condition or state. Example:

• A virtual machine’s current snapshot is above 2GB in size.

• A host is using 90 percent of its total memory.

• A datastore has been disconnected from all hosts.

Event – Monitors events. Example:

• The health of a host’s hardware has changed.

• A license has expired in the datacenter.

• A host has left the vNetwork distributed switch.


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Configuring Condition Triggers

Condition triggers for a virtual machine


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Configuring Event Triggers

Event trigger for a host


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Configuring Reporting Options

Use the Reporting pane to avoid needless re-alarms.


Avoid smallfluctuations.

Avoid repeats.

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Configuring Actions

Every alarm type has these actions:

Send a notification email, send a notification trap, or run a command.

Virtual machine alarms and host alarms have more actions.


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Configuring vCenter Server Notifications

In the menu bar, select Administration > vCenter Server Settings.


Select SNMP to specify trap destinations.

Select Mail to set SMTP parameters.

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Viewing and Acknowledging Triggered Alarms


The Acknowledge Alarm feature is used to track when triggered alarms are addressed.

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Lab 17

In this lab, you will demonstrate the vCenter Server alarm feature.

1. Create a virtual machine alarm that monitors for a condition.

2. Create a virtual machine alarm that monitors for an event.

3. Trigger virtual machine alarms and acknowledge them.

4. Disable virtual machine alarms.


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Create alarms with condition-based triggers.

Create alarms with event-based triggers.

View and acknowledge triggered alarms.

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Key Points

The VMkernel has built-in mechanisms (such as CPU load balancing and transparent page sharing) for managing the CPU and memory allocation on an ESX/ESXi host.

The Performance tab allows you to monitor a host or virtual machine’s performance in real time or over a period of time.

Use alarms to monitor your vCenter Server inventory. Alarms notify you when selected events or conditions have occurred.


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VS5ICM_M10_ResourceMonitoring

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