© 2010 VMware Inc. All rights reserved High Availability Module 12.

© 2010 VMware Inc. All rights reserved

High Availability

Module 12

Module 12-2


Operations

You Are Here

vSphere Environment

High Availability

Introduction to VMware Virtualization

VMware ESX and ESXi

VMware vCenter Server

Networking

Storage

Virtual Machines

Access Control

Resource Monitoring

Data Protection

Scalability

Patch Management

Installing VMware ESX and ESXi

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

Module 12-3


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.


Module 12-4


Module Lessons

Lesson 1: High Availability

Lesson 2: Managing VMware HA

Lesson 3: FT


Module 12-5


Lesson 1:High Availability


Module 12-6


Lesson Objectives

Describe VMware® solutions for:

• High availability

• Fault tolerance

Configure a VMware High Availability cluster


Module 12-7


High Availability and Fault Tolerance

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

A fault-tolerant system is designed so that, in the event of an unplanned outage, a backup component can immediately take over with no loss of service.

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?


Module 12-8


VMware Availability and Fault Tolerance Solutions

Availability features in VMware vSphere™:

Storage availability using multipathing

Network availability using network interface card (NIC) teaming

VMware vMotion™ and Storage vMotion

VMware HA

VMware Fault Tolerance (FT)

Support for MSCS clustering

VMware availability product:

VMware vCenter™ Site Recovery Manager:

• Decreases planned and unplanned downtime. SRM protects all of your important systems and applications with disaster recovery.


Module 12-9


VMware HA, FT, and MSCS Clustering

VMware HA FT MSCS clustering

Level of availability High availability Fault tolerance High availability

Amount of downtime Minimal Zero Minimal

Guest operating systems

supported

Works with all supported guest

operating systems

Works with all supported guest

operating systems

Works with Windows operating

systems

VMware ESX™/ESXi

hardware supported

Works with all supported ESX/ESXi hardware

Widely compatibleLimited to hardware

supported by Microsoft

Uses

Use to provide high availability for all

your virtual machines.

Use to provide fault tolerance to your

critical virtual machines.

Use to provide high availability to application services.


Module 12-10


vCenter Server Availability

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 VMware HA to protect the vCenter Server virtual machine.

Use VMware vCenter Server Heartbeat.


Module 12-11


VMware HA

VMware HA:

Provides automatic restart of virtual machines in case of physical host failures

Provides high availability while reducing the need for passive standby hardware and dedicated administrators

Provides support for virtual machine failures with virtual machine monitoring and FT

Is configured, managed, and monitored through vCenter Server

A cluster enabled for VMware HA and DRS can have:

Up to 32 hosts per cluster

Up to 320 virtual machines per host (regardless of the number of hosts/cluster)

Up to 3,000 virtual machines per cluster


Module 12-12


VMware HA in Action


vCenter Server

LUN 6LUN 5

LUN 4LUN 3LUN 2

LUN 1

host host host

virtual machine A

virtual machine B

virtual machine C

virtual machine D

virtual machine E

virtual machine F

virtual machine A virtual machine B

Module 12-13


Using VMware HA and DRS Together

Using VMware HA and DRS results in fast rebalancing of virtual machines after VMware HA has restarted virtual machines to different hosts.

Reasons why VMware HA might not be able to fail over virtual machines:

VMware HA admission control is disabled and VMware Distributed Power Management is enabled.

Required Virtual Machines to Hosts affinity rule prevents VMware HA from failing over.

Sufficient aggregated resources exist, but they are fragmented across hosts.

In such cases, VMware HA uses DRS to try to adjust the cluster by:

Bringing hosts out of standby mode

Migrating virtual machines to defragment the resources


Module 12-14


Detecting a Host Failure

The VMware HA agent monitors the heartbeats between the primary and the secondary hosts to detect host failure.

A heartbeat is sent every second (by default) over the heartbeat network.

On ESXi hosts, the management network is used.

On ESX hosts, the service console network is used.


Module 12-15


Host Isolation

If a host in the cluster loses its connection to the heartbeat network but the host continues running, the host is isolated from the cluster.

VMware HA waits 12 seconds before

deciding that a host is isolated.


virtual machinevirtual machine

virtual machine

virtual machine

virtual machine

virtual machine

Module 12-16


Architecture of a VMware HA Cluster


vCenter

Server

host host host

vCenterServeragent

VMware HAagent

vCenterServeragent

vCenterServeragent

VMware HAagent

VMware HAagent

Module 12-17


Enabling VMware HA

Enable VMware HA by creating a cluster or modifying a DRS cluster.


Module 12-18


Configuring VMware HA Settings

Disable Host Monitoring when

performing maintenance

activities on the host.

Admission control helps ensure sufficient resources to provide

high availability.


Module 12-19


Admission Control Policy Choices

Policy Description Recommended use

Host failures cluster tolerates

Reserves enough resources to tolerate specified number of

host failures

When virtual machines have similar CPU and memory reservations

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

Specify a failover hostDedicates a host

exclusively for failover service

To accommodate organizational policies

that dictate the use of a passive failover host


Module 12-20


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 when a

host loses the management (or service console) network but

continues running.


Module 12-21


Configuring Virtual Machine Monitoring

Restart 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.


Module 12-22


Monitoring Cluster Status

The Cluster Operational Status window displays the current VMware HA operational status, including the specific status and errors for each primary and secondary host in the cluster.


cluster’s Summary tab

Module 12-23


Lab 23

In this lab, you will demonstrate VMware HA functionality.

1. Create a cluster enabled for VMware HA.

2. Test VMware HA functionality.

3. Prepare for the next lab.


Module 12-24


Lesson Summary

Describe VMware solutions for:

• High availability

• Fault tolerance

Configure a VMware HA cluster


Module 12-25


Lesson 2:Managing VMware HA


Module 12-26


Lesson Objectives

Configure VMware HA advanced options

Configure redundant heartbeat networks

Configure redundant isolation test addresses

View the status of cluster operations

Follow best practices when configuring VMware HA clusters


Module 12-27


Planning Resources for a VMware HA/DRS Cluster

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

How much reserved capacity remains?


Module 12-28


Importance of Redundant Heartbeat Networks

In a VMware HA cluster, heartbeats are:

Sent between the primary and the secondary hosts

Used to determine if a primary host failed

Sent over the heartbeat network

The heartbeat network is:

On ESXi hosts, the management network

On ESX hosts, the service console network

Redundant heartbeat networks:

Allow for the reliable detection of failures

Help prevent isolation conditions from occurring


Module 12-29


Redundancy Using NIC Teaming

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


NIC teaming on an ESXi host

Module 12-30


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.

On ESX hosts, add one or more service console networks.


Module 12-31


How Hosts Test for Isolation

An isolation address is an IP address that is pinged to determine whether an ESX/ESXi host is isolated from the network.

Hosts in the VMware HA cluster test themselves for isolation by pinging the isolation address.

By default, ESXi hosts ping the VMkernel gateway IP address.

By default, ESX hosts ping the service console default gateway IP address.

As a best practice, configure redundant isolation addresses.


Module 12-32


Configuring Isolation Addresses

To configure more isolation addresses, set das.isolationaddress#.

When more isolation addresses are

configured, increase the value of

das.failuredetectiontime.

To prevent use of the default isolation address, set

das.usedefaultisolationaddress.

Ensure that your isolation

addresses are reliable IP

addresses.


Module 12-33


Network Configuration and Maintenance

Before changing the networking configuration on the ESX/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.


Module 12-34


Lab 24

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

1. Use the Resource Allocation tab to determine resource use.

2. Manage VMware HA slot size.

3. Configure a VMware HA cluster with strict admission control.

4. Configure a VMware HA cluster with flexible admission control.


Module 12-35


Lab 25 (Optional)

Do not perform this lab unless agreed to by your instructor.

In this lab, you will configure VMware HA network redundancy.

1. Enable technical support mode on an ESXi host.

2. Test default VMware HA failure detection time.

3. Modify and test VMware HA failure detection time.

4. Configure management network redundancy.

5. Configure VMware HA host isolation response.

6. Test network isolation functionality.


Module 12-36


Lesson Summary

Configure VMware HA advanced options

Configure redundant heartbeat networks

Configure redundant isolation test addresses

View the status of cluster operations

Follow best practices when configuring VMware HA clusters


Module 12-37


Lesson 3:FT


Module 12-38


Lesson Objectives

Compare VMware HA, FT, and MSCS clustering

List FT requirements and limitations

Describe FT operation

Configure, monitor, and test a fault-tolerant virtual machine


Module 12-39


What Is FT?

FT:

Provides a higher level of business continuity than VMware 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

Custom applications that have no other way of doing clustering

Cases where high availability might be provided through Microsoft Cluster Service but MSCS is too complicated to configure and maintain

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.


Module 12-40


FT in Action


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

primary VM

secondaryVM

newprimary

VM

new secondary

VM

vLockstep technology vLockstep technology

Module 12-41


Requirements for FT

Component FT requirement

vSphere configuration

• Host certificate checking enabled on all hosts• Hardware certified for FT

Storage• Virtual machines stored on shared storage• Virtual machines provisioned with thick virtual disks• Virtual machines not stored on physical RDMs

Networking• Minimum of two gigabit NICs, one for vMotion and one for FT logging. Three or more NICs are recommended.

Processor

• Uniprocessor virtual machines• Hosts processors from FT-compatible processor group• Virtual machines running a supported guest operating system

Host BIOS• Hardware Virtualization enabled• Same instruction set extension configuration applied to all hosts


Module 12-42


How FT Works

VMkernel VMkernelVMM VMM

primary

virtual machine

secondary

virtual machine

record logs

read/write read

single copy of disks on shared storage

Log update? Log read?

log bufferlog buffer

Heartbeat?


Module 12-43


FT Guidelines

Check the requirements and limitations of FT.

Ensure enough ESX/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


Module 12-44


Enabling FT Logging on a Host


For each ESX/ESXi host in the cluster, create a VMkernel networking interface to use for FT logging.

enabling FT logging on a vNetwork standard switch

Module 12-45


Enabling FT on a Virtual Machine


virtual machine’s Summary tab

After you turn on FT, the Summary

tab on the primary virtual machine

reports FT information.

Module 12-46


Managing Virtual Machines Enabled for FT


Use the commands from the shortcut menu to test and manage the virtual machine enabled for FT.

Module 12-47


Lab 26 and eLearning Activity

Do lab 26 if you are using a lab environment that supports FT.

In this lab, you will configure FT for a virtual machine and verify that FT works.

1. Enable FT logging.

2. Activate FT.

3. Test FT.

4. Disable FT.

Otherwise, perform the eLearning activity:

http://mylearn.vmware.com/register.cfm?course=73276


Module 12-48


Lesson Summary


Compare VMware HA, FT, and MSCS clustering

List FT requirements and limitations

Describe FT operation

Configure, monitor, and test a fault-tolerant virtual machine

Module 12-49


Key Points

A good practice is to enable both DRS and VMware HA in a cluster.

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.


© 2010 VMware Inc. All rights reserved High Availability Module 12.

Documents

Transcript of © 2010 VMware Inc. All rights reserved High Availability Module 12.