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© 2010 VMware Inc. All rights reserved
High Availability
Module 12
Module 12-2
© 2010 VMware Inc. All rights reserved
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
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-4
© 2010 VMware Inc. All rights reserved
Module Lessons
Lesson 1: High Availability
Lesson 2: Managing VMware HA
Lesson 3: FT
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-5
© 2010 VMware Inc. All rights reserved
Lesson 1:High Availability
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-6
© 2010 VMware Inc. All rights reserved
Lesson Objectives
Describe VMware® solutions for:
• High availability
• Fault tolerance
Configure a VMware High Availability cluster
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-7
© 2010 VMware Inc. All rights reserved
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?
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-8
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-9
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-10
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-11
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-12
© 2010 VMware Inc. All rights reserved
VMware HA in Action
VMware vSphere 4.1: Install, Configure, Manage – Revision A
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
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-14
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-15
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
virtual machinevirtual machine
virtual machine
virtual machine
virtual machine
virtual machine
Module 12-16
© 2010 VMware Inc. All rights reserved
Architecture of a VMware HA Cluster
VMware vSphere 4.1: Install, Configure, Manage – Revision A
vCenter
Server
host host host
vCenterServeragent
VMware HAagent
vCenterServeragent
vCenterServeragent
VMware HAagent
VMware HAagent
Module 12-17
© 2010 VMware Inc. All rights reserved
Enabling VMware HA
Enable VMware HA by creating a cluster or modifying a DRS cluster.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-18
© 2010 VMware Inc. All rights reserved
Configuring VMware HA Settings
Disable Host Monitoring when
performing maintenance
activities on the host.
Admission control helps ensure sufficient resources to provide
high availability.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-19
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-20
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-21
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-22
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
cluster’s Summary tab
Module 12-23
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-24
© 2010 VMware Inc. All rights reserved
Lesson Summary
Describe VMware solutions for:
• High availability
• Fault tolerance
Configure a VMware HA cluster
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-25
© 2010 VMware Inc. All rights reserved
Lesson 2:Managing VMware HA
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-26
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-27
© 2010 VMware Inc. All rights reserved
Planning Resources for a VMware HA/DRS Cluster
How much CPU and memory resources is the cluster using now?
How much reserved capacity remains?
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-28
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-29
© 2010 VMware Inc. All rights reserved
Redundancy Using NIC Teaming
You can use NIC teaming to create a redundant heartbeat network on ESX/ESXi hosts.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
NIC teaming on an ESXi host
Module 12-30
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-31
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-32
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-33
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-34
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-35
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-36
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-37
© 2010 VMware Inc. All rights reserved
Lesson 3:FT
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-38
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-39
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-40
© 2010 VMware Inc. All rights reserved
FT in Action
VMware vSphere 4.1: Install, Configure, Manage – Revision A
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
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-42
© 2010 VMware Inc. All rights reserved
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?
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-43
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-44
© 2010 VMware Inc. All rights reserved
Enabling FT Logging on a Host
VMware vSphere 4.1: Install, Configure, Manage – Revision A
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
© 2010 VMware Inc. All rights reserved
Enabling FT on a Virtual Machine
VMware vSphere 4.1: Install, Configure, Manage – Revision A
virtual machine’s Summary tab
After you turn on FT, the Summary
tab on the primary virtual machine
reports FT information.
Module 12-46
© 2010 VMware Inc. All rights reserved
Managing Virtual Machines Enabled for FT
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Use the commands from the shortcut menu to test and manage the virtual machine enabled for FT.
Module 12-47
© 2010 VMware Inc. All rights reserved
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
VMware vSphere 4.1: Install, Configure, Manage – Revision A
Module 12-48
© 2010 VMware Inc. All rights reserved
Lesson Summary
VMware vSphere 4.1: Install, Configure, Manage – Revision A
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
© 2010 VMware Inc. All rights reserved
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.
VMware vSphere 4.1: Install, Configure, Manage – Revision A