vs5icm_m11_highavailability

© 2011 VMware Inc. All rights reserved

High Availability and Fault Tolerance

Module 11

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You Are Here

VMware vSphere: Install, Configure, Manage – Revision A

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

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Importance


Most organizations rely on computer-based services like email, databases, and Web-based applications. The failure of any of these services can mean lost productivity and revenue. Configuring highly available, computer-based services is extremely important for an organization to remain competitive in contemporary business environments.

With VMware vSphere® 5, a new high availability architecture has been released.

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Module Lessons


Lesson 1: Introduction to vSphere High Availability

Lesson 2: Configuring vSphere High Availability

Lesson 3: vSphere High Availability Architecture

Lesson 4: Introduction to Fault Tolerance

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Lesson 1:Introduction to

vSphere High Availability


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Learner Objectives


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

Describe the various options that you can configure to ensure high availability in a vSphere 5 environment.

Discuss the response of vSphere High Availability when a VMware® ESXi™ host, a virtual machine, or an application fails.

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VMware Offers Protection at Every Level

NIC Teaming, Storage

Multipathing

VMware vSphere® vMotion®, DRS

vSphere Storage VMotion

Site Recovery Manager

Component Server Storage Data Site

3rd-Party Backup Solutions,

VMware Data Recovery

VMFS

VMFS

High Availability & Fault Tolerance

vSphere 5

VM

VMVM

Protection against hardware failures Planned maintenance with zero downtime Protection against unplanned downtime

and disasters

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vCenter Server Availability - Recommendations


Make VMware vCenter Server™ and the components it relies on highly available.

vCenter Server relies on:

vCenter Server database:

• Cluster the database. Refer to the specific database documentation.

Active Directory structure:

• Set up with multiple redundant servers.

Methods for making vCenter Server available:

Use vSphere High Availability to protect the vCenter Server virtual machine.

Use VMware vCenter Server Heartbeat™.

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High Availability


A highly available system is one that is continuously operational for a desirably long length of time.

Level of availability Downtime per year

99% 87 hours (3.5 days)

99.9% 8.76 hours

99.99% 52 minutes

99.999% 5 minutes

What level of virtual machine availability is

important to you?

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vSphere High Availability


vSphere HA

Level of availability High availability

Amount of downtime Minimal

Guest operating systems supported Works with all supported guest operating systems

VMware ESXi hardware supported Works with all supported ESXi hardware

UsesUse to provide high availability for the virtual machines that require that level of protection.

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vSphere HA Failure Scenarios

ESXi host failure

Guest OS failure

Application failure

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LUN 1 LUN 2 LUN 3

High Availability Failure Scenario - Host


virtual machine A

virtual machine B

virtual machine C

virtual machine F

vCenter Server

ESXi host ESXi hostESXi host

virtual machine D

virtual machine E

virtual machine A virtual machine B

When a host fails, vSphere HA restarts the affected virtual machines on other hosts

= vSphere HA cluster

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LUN 1 LUN 2 LUN 3

High Availability Failure Scenario – Guest Operating System


vCenter Server

ESXi host ESXi host


ESXi host

When a virtual machine stops sending heartbeats or the virtual machine process crashes (vmx), vSphere HA resets the virtual machine

virtual machine C

VMware tools VMware tools

virtual machine E

VMware tools

virtual machine F

VMware tools

virtual machine A

VMware tools

virtual machine BVMware tools

virtual machine D

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LUN 1 LUN 2 LUN 3

HA Failure Scenario - Application


vCenter Server

ESXi host ESXi hostESXi host

virtual machine E

application When an application fails, vSphere HA restarts the affected virtual machine on the same host.

Requires VMware Tools to be installed

virtual machine C

application

virtual machine F

applicationvirtual machine D

application

virtual machine A

application

virtual machine B

application


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Review of Learner Objectives


You should be able to do the following:

Describe the various options that you can configure to ensure high availability in a vSphere 5 environment.

Discuss the response of vSphere High Availability when an ESXi host, a virtual machine, or an application fails.

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Lesson 2:Configuring vSphere High Availability


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Learner Objectives



Configure a vSphere HA cluster.

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Enabling vSphere HA


Enable vSphere HA by creating a cluster or modifying a vSphere Distributed Resource Scheduler (DRS) cluster.

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Configuring vSphere HA Settings


Disable Host Monitoring when

performing maintenance

on any cluster/host. Enabled is the default setting.

Admission Controlrefers to the amount of available resourcesthat can be used to

start virtual machineson a specific ESXi

host. The default setting

is to disallow power and other operations that will violate the

set Admission Control Policy.

Admission control helps ensure sufficient resources to provide

high availability.Default setting is Host failures the cluster tolerates.

VMware recommended

setting

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Admission Control Policy Choices


Policy Description Recommended use

Percentage of cluster resources reserved as failover spare capacity

Reserves specified percentage of total capacity

When virtual machines have highly variable CPU and memory reservations

Host failures cluster tolerates

Reserves enough resources to tolerate specified number of host failures

When virtual machines have similar CPU/memory reservations and similar memory overheads

Specify a failover host Dedicates a host exclusively for failover service

To accommodate organizational policies that dictate the use of a passive failover host

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Configuring Virtual Machine Options


Configure options at the cluster level or per virtual machine.

VM restart priority determines relative order in which virtual machines are restarted after a host

failure.

Host Isolation response determines what happens to virtual machines when a host loses

the management network but continues running.

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Configuring Virtual Machine Monitoring


Reset a virtual machine if its VMware Tools

heartbeat or VMware Tools application

heartbeats are not received.

Determine how quickly failures are

detected.

Set monitoring sensitivity for individual virtual machines.

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Importance of Redundant Heartbeat Networks


In a vSphere HA cluster, heartbeats are:

Sent between the master and the slave hosts

Used to determine if a master or slave host has failed

Sent over a heartbeat network

The heartbeat network is:

Implemented using a VMkernel port marked for management

Redundant heartbeat networks:

Allow for the reliable detection of failures

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Redundancy Using NIC Teaming


You can use NIC teaming to create a redundant heartbeat network on ESXi hosts.

Both port groups must be VMkernel ports.

NIC teaming on an ESXi host

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Redundancy Using Additional Networks


You can also create redundancy by configuring more heartbeat networks:

On ESXi hosts, add one or more VMkernel networks marked for management traffic.

Configure port group with these settings:

Set Load Balancing to originating port ID.

Do not enable Failback.

Configure port group with active/standby failover.

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Network Configuration and Maintenance


Before changing the networking configuration on the ESXi hosts (adding port groups, removing vSwitches):

Deselect Enable Host Monitoring.

Place the host inmaintenance mode.

These steps prevent unwanted attempts to fail over virtual machines.

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Cluster Resource Allocation Tab


How much CPU and memory resources is the cluster using now?

How much reserved capacity remains?

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Monitoring Cluster Status


The vSphere HA Cluster Status window displays details about host operational status, virtual machine protection, and heartbeat datastores

The Configuration Issues window displays the current vSphere HA operational status, including the specific status and errors for each master and slave host in the cluster.

cluster’s Summary tab

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Lab 18


In this lab, you will modify slot sizes and admission control.

1. Create a cluster enabled for vSphere HA.

2. Add your ESXi host to a cluster.

3. Test vSphere HA functionality.

4. Prepare for the next lab.

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Configure a vSphere HA cluster.

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Lesson 3:vSphere High Availability Architecture


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Learner Objectives



Describe heartbeat mechanisms used by vSphere HA.

Identify and discuss additional failure scenarios.

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vSphere HA Architecture: Agent Communication


vCenter Server

ESXi host (slave)

FDM

ESXi host (master)

FDM

ESXi host (slave)

FDM

vpxd

hostdhostdhostd

datastore datastoredatastore

= Management network

vpxa vpxa vpxa

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vSphere HA Architecture: Network Heartbeats


vCenter Server

virtual machine A

virtual machine B

virtual machine C

virtual machine D

virtual machine E

virtual machine F

ESXi host(slave)

ESXi host(slave)

ESXi host(master)

NAS/NFS VMFS Local

Management network 1


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vSphere HA Architecture: Datastore Heartbeats




vCenter Server

virtual machine A

virtual machine B

virtual machine C

virtual machine D

virtual machine E

virtual machine F

ESXi host(slave)

ESXi host(master)

ESXi host(slave)

NAS/NFS VMFS Local

Cluster Edit Settings Window

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Additional HA Failure Scenarios


Slave host failure

Master host failure

Host isolation

Management network failures

• Network partition

• Network isolation

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Failed Slave Host


vCenter Server

virtual machine A

virtual machine B

virtual machine C

virtual machine D

virtual machine E

virtual machine F

ESXi host(slave)

ESXi host (master)

ESXi host(slave)

NAS/NFS(lock file)

?

file locks file locks

primary heartbeat network

alternate heartbeat network

VMFS(heartbeat region)

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Failed Master Host


virtual machine A

virtual machine B

virtual machine C

virtual machine D

virtual machine E

virtual machine F

ESXi hostRole: slaveMOID: 98

ESXi hostRole: masterMOID: 99

file locks

NAS/NFS(lock file)

?

file locks

vCenter Serverprimary heartbeat network

alternate heartbeat network

MOID = managed object ID

default gateway(isolation address)

ESXi hostRole: slaveMOID: 100

VMFS(heartbeat region)

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Isolated Host


virtual machine A

virtual machine B

virtual machine C

virtual machine D

virtual machine E

virtual machine F

ESXi host ESXi host


ESXi host

The host is not observing any election traffic on the management and cannot ping its isolation address(es), the host is isolated.

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Design Considerations

Host isolation events can be minimized through good design

Implement redundant heartbeat networks

Implement redundant isolation addresses

If host isolation events do occur, good design enables vSphere HA to determine whether the isolated host is still alive

Implement datastores so that they are separated from the management network using one or both of the following approaches:

• Fibre Channel over fibre optic

• Physically separating your IP storage network from the management network

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Network Partition



virtual machine A

virtual machine B

ESXi hostMASTER

virtual machine C

virtual machine D

ESXi hostSLAVE

virtual machine E

virtual machine F

ESXi hostSLAVE

virtual machine G

virtual machine H

ESXi hostSLAVE

vCenter Server

MASTER

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Describe heartbeat mechanisms used by vSphere HA

Identify and discuss additional failure scenarios

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Lesson 4:Introduction to Fault Tolerance


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Learner Objectives



List Fault Tolerance requirements and limitations.

Describe Fault Tolerance operation.

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What Is Fault Tolerance (FT)?


FT:

A fault-tolerant system is designed so that, in the event of an unplanned outage, a backup virtual machine can immediately take over with no loss of service. (The backup virtual machine is called a secondary virtual machine.)

• Provides a higher level of business continuity than vSphere HA

• Provides zero downtime and zero data loss for applications

FT can be used for any application that needs to be available at all times.

FT can be used with DRS:

Fault-tolerant virtual machines benefit from better initial placement and are included in the cluster’s load-balancing calculations.

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VMware Fault Tolerance


Fault Tolerance

Level of availability Fault tolerance

Amount of downtime Zero

Guest operating systems supported Works with all supported guest operating systems

ESXi hardware supported Widely compatible

Uses Use to provide fault tolerance to your critical virtual machines.

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Fault Tolerance in Action


FT provides zero-downtime, zero-data-loss protection to virtual machines in a vSphere HA cluster.

primary VM

secondaryVM

newprimary

VM

new secondary

VM

vLockstep technology vLockstep technology

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Fault Tolerance Guidelines


Check the requirements and limitations of FT.

Ensure enough ESXi hosts for fault-tolerant virtual machines:

No more than four fault-tolerant virtual machines (primaries or secondaries) on any single host

Store ISOs on shared storage for continuous access:

Especially if used for important operations

Disable BIOS-based power management:

Prevents the secondary virtual machine from having insufficient CPU resources

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Enabling Fault Tolerance on a Virtual Machine


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List Fault Tolerance requirements and limitations.

Describe Fault Tolerance operation.

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Key Points


vSphere HA restarts virtual machines on the remaining hosts in the cluster.

Hosts in vSphere HA clusters have a master/slave relationship.

Implement redundant heartbeat networks either with NIC teaming or by creating additional heartbeat networks.

FT provides zero downtime for applications that need to be available at all times.

vs5icm_m11_highavailability

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