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vSphere AvailabilityUpdate 1

VMware vSphere 6.5VMware ESXi 6.5

vCenter Server 6.5

This document supports the version of each product listed andsupports all subsequent versions until the document isreplaced by a new edition. To check for more recent editions ofthis document, see


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You can find the most up-to-date technical documentation on the VMware Web site at:

The VMware Web site also provides the latest product updates.

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Copyright 20092017 VMware, Inc. All rights reserved. Copyright and trademark information.

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About vSphere Availability 5

1 Business Continuity and Minimizing Downtime 7

Reducing Planned Downtime 7Preventing Unplanned Downtime 8vSphere HA Provides Rapid Recovery from Outages 8vSphere Fault Tolerance Provides Continuous Availability 9Protecting the vCenter Server Appliance with vCenter High Availability 10Protecting vCenter Server with VMware Service Lifecycle Manager 10

2 Creating and Using vSphere HA Clusters 11

How vSphere HA Works 11vSphere HA Admission Control 19vSphere HA Interoperability 24Creating a vSphere HA Cluster 27Configuring vSphere Availability Settings 29Best Practices for VMware vSphere High Availability Clusters 38

3 Providing Fault Tolerance for Virtual Machines 41

How Fault Tolerance Works 41Fault Tolerance Use Cases 42Fault Tolerance Requirements, Limits, and Licensing 42Fault Tolerance Interoperability 43Preparing Your Cluster and Hosts for Fault Tolerance 45Using Fault Tolerance 47Best Practices for Fault Tolerance 51Legacy Fault Tolerance 53

4 vCenter High Availability 57

Plan the vCenter HA Deployment 58Configure the Network 63Configure vCenter HA With the Basic Option 64Configure vCenter HA With the Advanced Option 65Manage the vCenter HA Configuration 68Troubleshoot Your vCenter HA Environment 73Patching a vCenter High Availability Environment 78

5 Using Microsoft Clustering Service for vCenter Server on Windows High

Availability 79Benefits and Limitations of Using MSCS 79Upgrade vCenter Server in an MSCS Environment 79

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Configure MSCS for High Availability 81

Index 83

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About vSphere Availability

vSphere Availability describes solutions that provide business continuity, including how to establish vSphere

High Availability (HA) and vSphere Fault Tolerance.

Intended AudienceThis information is for anyone who wants to provide business continuity through the vSphere HA and FaultTolerance solutions. The information in this book is for experienced Windows or Linux systemadministrators who are familiar with virtual machine technology and data center operations.

Task instructions in this guide are based on the vSphere Web Client. You can also perform most of the tasksin this guide by using the new vSphere Client. The new vSphere Client user interface terminology, topology,and workflow are closely aligned with the same aspects and elements of the vSphere Web Client userinterface. You can apply the vSphere Web Client instructions to the new vSphere Client unless otherwiseinstructed.

Note Not all functionality in the vSphere Web Client has been implemented for the vSphere Client in thevSphere 6.5 release. For an up-to-date list of unsupported functionality, see Functionality Updates for thevSphere Client Guide at

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Business Continuity and MinimizingDowntime 1

Downtime, whether planned or unplanned, brings considerable costs. However, solutions that ensurehigher levels of availability have traditionally been costly, hard to implement, and difficult to manage.

VMware software makes it simpler and less expensive to provide higher levels of availability for importantapplications. With vSphere, you can increase the baseline level of availability provided for all applicationsand provide higher levels of availability more easily and cost effectively. With vSphere, you can:

n Provide high availability independent of hardware, operating system, and applications.

n Reduce the planned downtime for common maintenance operations.

n Provide automatic recovery in cases of failure.

vSphere makes it possible to reduce planned downtime, prevent unplanned downtime, and recover rapidlyfrom outages.

This chapter includes the following topics:

n Reducing Planned Downtime, on page 7

n Preventing Unplanned Downtime, on page 8

n vSphere HA Provides Rapid Recovery from Outages, on page 8

n vSphere Fault Tolerance Provides Continuous Availability, on page 9

n Protecting the vCenter Server Appliance with vCenter High Availability, on page 10

n Protecting vCenter Server with VMware Service Lifecycle Manager, on page 10

Reducing Planned DowntimePlanned downtime typically accounts for over 80% of data center downtime. Hardware maintenance, servermigration, and firmware updates all require downtime for physical servers. To minimize the impact of thisdowntime, organizations are forced to delay maintenance until inconvenient and difficult-to-scheduledowntime windows.

vSphere makes it possible for organizations to dramatically reduce planned downtime. Because workloadsin a vSphere environment can be dynamically moved to different physical servers without downtime orservice interruption, server maintenance can be performed without requiring application and servicedowntime. With vSphere, organizations can:

n Eliminate downtime for common maintenance operations.

n Eliminate planned maintenance windows.

n Perform maintenance at any time without disrupting users and services.

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The vSphere vMotion and Storage vMotion functionality in vSphere makes it possible for organizations toreduce planned downtime because workloads in a VMware environment can be dynamically moved todifferent physical servers or to different underlying storage without service interruption. Administrators canperform faster and completely transparent maintenance operations, without being forced to scheduleinconvenient maintenance windows.

Preventing Unplanned DowntimeWhile an ESXi host provides a robust platform for running applications, an organization must also protectitself from unplanned downtime caused from hardware or application failures. vSphere builds importantcapabilities into data center infrastructure that can help you prevent unplanned downtime.

These vSphere capabilities are part of virtual infrastructure and are transparent to the operating system andapplications running in virtual machines. These features can be configured and utilized by all the virtualmachines on a physical system, reducing the cost and complexity of providing higher availability. Keyavailability capabilities are built into vSphere:

n Shared storage. Eliminate single points of failure by storing virtual machine files on shared storage,such as Fibre Channel or iSCSI SAN, or NAS. The use of SAN mirroring and replication features can beused to keep updated copies of virtual disk at disaster recovery sites.

n Network interface teaming. Provide tolerance of individual network card failures.

n Storage multipathing. Tolerate storage path failures.

In addition to these capabilities, the vSphere HA and Fault Tolerance features can minimize or eliminateunplanned downtime by providing rapid recovery from outages and continuous availability, respectively.

vSphere HA Provides Rapid Recovery from OutagesvSphere HA leverages multiple ESXi hosts configured as a cluster to provide rapid recovery from outagesand cost-effective high availability for applications running in virtual machines.

vSphere HA protects application availability in the following ways:

n It protects against a server failure by restarting the virtual machines on other hosts within the cluster.

n It protects against application failure by continuously monitoring a virtual machine and resetting it inthe event that a failure is detected.

n It protects against datastore accessibility failures by restarting affected virtual machines on other hostswhich still have access to their datastores.

n It protects virtual machines against network isolation by restarting them if their host becomes isolatedon the management or vSAN network. This protection is provided even if the network has becomepartitioned.

Unlike other clustering solutions, vSphere HA provides the infrastructure to protect all workloads with theinfrastructure:

n You do not need to install special software within the application or virtual machine. All workloads areprotected by vSphere HA. After vSphere HA is configured, no actions are required to protect newvirtual machines. They are automatically protected.

n You can combine vSphere HA with vSphere Distributed Resource Scheduler (DRS) to protect againstfailures and to provide load balancing across the hosts within a cluster.

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vSphere HA has several advantages over traditional failover solutions:

Minimal setup After a

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