resource monitoring

Resource Monitoring Module 9

Module 2-2

You Are Here

VMware vSphere 4.1: Install, Configure, Manage – Revision A

vSphere Environment

Introduction to VMware Virtualization

VMware ESX and ESXi

VMware vCenter Server

Networking

Storage

Virtual Machines

Operations

Access Control

Data Protection

Scalability

High Availability

Patch Management

Installing VMware ESX and ESXi

Resource Monitoring

Module 2-3

Importance

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

Module 2-4

Module Lessons

Lesson 1: Resource Controls and Resource Pools Lesson 2: Virtual CPU and Memory Concepts Lesson 3: Monitoring Resource Usage Lesson 4: Using Alarms

Module 2-5

Lesson 1:Resource Controls and Resource Pools

Module 2-6

Lesson Objectives

Describe resource allocation settings for: • CPU• Memory• Storage I/O

Create a resource pool

Module 2-7

Systems for Optimizing Virtual Machine Resource Use

Managed by VMkernelConfigured by virtual machine owner

Adjustable by administrator

CPU cycles

• Hyperthreading• Load balancing• NUMA

• VMware® Virtual SMP

• Limit• Reservation• Share allocation

• Transparent page sharing

• vmmemctl• Memory compression• VMkernel swap files

for virtual machines

• Available memory

• Limit• Reservation• Share allocation

Disk bandwidth • Virtual machine

file location• Storage I/O Control• Multipathing

Network bandwidth

• NIC teaming

• Traffic shaping• Network I/O Control

(distributed virtual switch only)

Module 2-8

Resource Management

Resource management is the allocation of resources from providers (hosts, clusters, and resource pools) to consumers (virtual machines). Resources include CPU, memory, storage, and network.

Resource management: Resolves resource overcommitment Prevents virtual machines from monopolizing resources Exploits undercommitted resources Controls the relative importance of virtual machines

Resource allocation settings: CPU and memory is controlled by using shares, limits, and reservations. Storage I/O is controlled by using shares and limits.

Module 2-9

Virtual Machine CPU Resource Settings

Limit (MHz): A cap on the consumption

of CPU time by this virtual machine

Reservation (MHz): A certain number of CPU

cycles reserved for this virtual machine

Shares: A value that specifies the

relative priority or importance of a virtual machine

Module 2-10

How Virtual Machines Compete for Resources

Proportional-share system for relative resource management: Applied during resource contention Prevents virtual machines from monopolizing resources Guarantees predictable resource shares

Number of shares

Change number of shares.

Power on VM.

Power off VM.

Module 2-11

Virtual Machine Memory Resource Settings

Available memory: Memory size defined when the

virtual machine was createdLimit (MB): A cap on the consumption of

physical memory by this virtual machine

Reservation (MB): A certain amount of physical

memory reserved for this virtual machine

Shares: A value that specifies the relative

priority or importance of a virtual machine

A virtual machine swap file covers the range between available memory and reservation.

Module 2-12

Virtual Machine Storage I/O Resource Settings

Storage I/O Control resource settings: Limit (IOPs):

• Cap on the storage I/O bandwidth for the virtual machine Shares:

• A value that shows relative importance of a virtual machine

Storage I/O Control: Must be enabled on the datastore Has several requirements

IOPS Iometer latencyVM1 1,500 20msVM2 1,500 21ms

IOPS Iometer latency1,080 31ms1,900 16ms

Example 1: Two VMs running Iometer(VM1:1,000 shares, VM2: 2,000 shares)

Without shares/limits With shares/limits

Module 2-13

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 VMware Distributed Resource Scheduler.It provides resources for virtual machines and child pools.

resource pools

rootresource

Module 2-14

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

Module 2-15

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.

Module 2-16

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.

Module 2-17

Resource Pool Example

Module 2-18

Resource Pools Example: CPU Shares

Module 2-19

Resource Pools Example: CPU Contention

Module 2-20

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

reservation: 1,200MHz

expandable? Yes

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

Module 2-21

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

reservation: 3,000MHz expandable reservation: No

VM1R=40

VM2R=30

Root resource pool

Total CPU: 10,200MHz Total memory: 3,000 MB

eCommerce Apps pool

eCommerce Web pool

expandable? No

expandable? Yes

Module 2-22

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

VM7R=500

VM3R=500

**200MHz used by Retail**

**full reservation used**

eCommerce Apps pool

eCommerce Web pool

expandable? Yes

Module 2-23

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?

Yes – Go to parent pool.

Succeed

FailNo

Module 2-24

Resource Pool Summary Tab

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

Module 2-25

Resource Allocation Tab

Click the resource pool’s Resource Allocation tab.

Module 2-26

Scheduling Changes to Resource Settings

Schedule a task to change the resource settings of a resource

pool or a virtual machine.

Module 2-27

Lab 14

In this lab, you will create and use resource pools on an ESXi host.1. Create a resource pool.2. Verify resource pool functionality.

Module 2-28

Lesson Summary

Describe resource allocation settings for:• CPU• Memory• Storage I/O

Create a resource pool

Module 2-29

Lesson 2:Virtual CPU and Memory Concepts

Module 2-30

Lesson Objectives

Identify the methods used by the VMkernel for optimizing CPU and memory usage

Module 2-31

Multicore Processors

Module 2-32

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.

Module 2-33

CPU Load Balancing

Module 2-34

Memory Virtualization Overview

The VMkernel manages a machine’s entire memory. Part of this memory is used by the VMkernel. Some memory is used by the service console (ESX only). The rest is available for use by virtual machines:

• Configured memory, plus overhead

Virtual machines can use more memory than the physical machine has available. This is called memory overcommitment.

Memory compression improves virtual machine performance when memory is overcommitted. When memory becomes overcommitted, virtual pages are

compressed and stored in memory. Compressed memory is faster to access than memory swapped

to disk.

Module 2-35

Transparent Page Sharing

The VMkernel detects identical pages in the memory of virtual machines and maps them to the same underlying physical page: No changes to guest

operating system requiredThe VMkernel treats the shared pages as copy-on-write: Read-only when shared Private copies after write

A best practice is to always keep transparent page sharing enabled.

hardware RAM

VM RAMVM RAMVM RAM

Module 2-36

vmmemctl: Balloon-Driver Mechanism

Deallocate memory from selected virtual machines when RAM is scarce.

Inflate balloon. (Driver demands

memory from guest OS.)

Guest is forced to page out to its own paging area.

The VMkernel reclaims memory.

Guest can page in. ESX/ESXi

grants memory.

Deflate balloon. (Driver relinquishes

memory.)

Ample memory.Balloon remains

uninflated.

Module 2-37

VMkernel Swap

Each powered-on virtual machine needs its own VMkernel swap file: Created when the virtual machine is

powered on. Deleted when the virtual machine is powered off.

Default location: same VMware vStorage VMFS volume as virtual machine’s boot disk.

Size is equal to the difference between the memory guaranteed to it, if any, and the maximum it can use.

Allows the VMkernel to swap out the virtual machine entirely if memory is scarce.

Use of VMkernel swap is a last resort. Performance will be noticeably slow.

Module 2-38

Ballooning Compared with VMkernel Swapping

Module 2-39

Lesson Summary

Identify the methods used by the VMkernel for optimizing CPU and memory usage

Module 2-40

Lesson 3:Monitoring Resource Usage

Module 2-41

Lesson Objectives

Monitor a virtual machine’s resource usage:• CPU• Memory• Disk• Network bandwidth

Module 2-42

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.

Module 2-43

Guest Operating System Monitoring Tools

Task ManagerIometer

Module 2-44

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.

Module 2-45

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

Module 2-46

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

Module 2-47

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.

Module 2-48

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

Module 2-49

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.

Module 2-50

Is the Host Memory-Constrained?

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

Module 2-51

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.

Module 2-52

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 typeHost Datastore FC, iSCSI, NFSHost Storage adapter FCHost Storage path FC, iSCSI

Virtual machine Datastore FC, iSCSI, NFSVirtual machine Virtual disk FC, iSCSI, NFS

Module 2-53

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.

Module 2-54

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.

Module 2-55

Lab 15

In this lab, you will see how CPU workload is reflected by system monitoring tools.1. Use vCenter Server to monitor CPU utilization.

Module 2-56

Lesson Summary

Monitor a virtual machine’s resource usage:• CPU• Memory• Disk• Network bandwidth

Module 2-57

Lesson 4:Using Alarms

Module 2-58

Lesson Objectives

Create alarms with condition-based triggers Create alarms with event-based triggers View and acknowledge triggered alarms

Module 2-59

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)

Module 2-60

Alarm Settings

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

Alarm types for:Virtual machines

HostsClusters

DatacentersDatastoresNetworks

Distributed switchesDistributed virtual port groups

Module 2-61

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.

Module 2-62

Configuring Condition Triggers

Condition triggers for a virtual machine

Module 2-63

Configuring Event Triggers

Event trigger for a host

Module 2-64

Configuring Reporting Options

Use the Reporting pane to avoid needless re-alarms.

Avoid small

fluctuations.

Avoid repeats.

Module 2-65

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.

Module 2-66

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.

Module 2-67

Viewing and Acknowledging Triggered Alarms

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

Module 2-68

Lab 16

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.

Module 2-69

Lesson Summary

Create alarms with condition-based triggers Create alarms with event-based triggers View and acknowledge triggered alarms

Module 2-70

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.

resource monitoring

virtual cpu

resource controls

resource poolsvmware

resource pool module

resource poolslesson

resource contention

virtual switch

virtual machinemodule

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