VMware vSphere Replication - 6.5 Instruction Manual

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Using VMware vSphere Replication

vSphere Replication 6.5

Using VMware vSphere Replication

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VMware, Inc. 2

About Using VMware vSphere Replication 4

Replicating Virtual Machines 5

How the Recovery Point Objective Affects Replication Scheduling 6

How the 5 Minute Recovery Point Objective Works 7

How Retention Policy Works 7

Replicating a Virtual Machine and Enabling Multiple Point in Time Instances 9

Using vSphere Replication with Virtual SAN Storage 9

Using vSphere Replication with vSphere Storage DRS 11

How vSphere Replication Synchronizes Data Between vCenter Server Sites During Initial

Configuration 11

Replicating Virtual Machines Using Replication Seeds 13

Replicating a Virtual Machine in a Single vCenter Server Instance 13

Best Practices For Using and Configuring vSphere Replication 14

Configure Replication for a Single Virtual Machine to vCenter Server 15

Configure Replication for Multiple Virtual Machines to vCenter Server 18

Move a Replication to a New vSphere Replication Server 20

Stop Replicating a Virtual Machine 21

Reconfiguring Replications 22

Monitoring and Managing Replications in vSphere Replication 26

View the Replication Summary for a Site 26

View Replication Reports for a Site 28

Identifying Replication Problems in the Issues Tab 30

Manage Target Sites 31

Manage vSphere Replication Servers 31

Performing a Recovery with vSphere Replication 33

Recover Virtual Machines by Using vSphere Replication 34

Failback of Virtual Machines in vSphere Replication 35

Troubleshooting vSphere Replication 36

Generate vSphere Replication Support Bundle 36

vSphere Replication Events and Alarms 37

Solutions for Common vSphere Replication Problems 41

VMware, Inc.

About Using VMware vSphere

Replication 1

Using vSphere Replication provides information about using VMware vSphere Replication.

Intended Audience

This information is intended for anyone who wants to protect the virtual machines in their virtual

infrastructure by using vSphere Replication.The information is written for experienced Windows or Linux

system administrators who are familiar with virtual machine technology and datacenter operations.

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Replicating Virtual Machines 2

With vSphere Replication you can replicate virtual machines from a source site to a target site.

You can set a recovery point objective (RPO) to a certain time interval depending on your data protection

needs. vSphere Replication applies all changes made to virtual machines configured for replication at the

source site to their replicas at the target site. This process reoccurs periodically to ensure that the replicas

at the target site are not older than the RPO interval that you set. See How the Recovery Point Objective

Affects Replication Scheduling.

To replicate a virtual machine using vSphere Replication, you must deploy the vSphere Replication

appliance at the source and target sites. A vSphere Replication infrastructure requires one

vSphere Replication appliance at each site.

The source and target sites must be connected for you to be able to configure replications. You cannot

perform replications if one of the sites is in the Connection issue state. For more details, see Site

Connection States Displayed in the vSphere Web Client in the vSphere Replication Installation and

Configuration guide. If the sites appear in the Not authenticated state, scheduled replications continue

as normal, but you cannot manage replications. See vSphere Replication Sites Appear in the Not

Authenticated State.

vSphere Replication does not support the recovery of multiple virtual machines from the same workflow.

Each recovery workflow is for an individual virtual machine.

You can configure replications for powered-off virtual machines, but the data synchronization begins when

the virtual machine is powered on. While the source virtual machine is powered off, the replication

appears in Not active status.

You cannot use vSphere Replication to replicate virtual machine templates.

This section includes the following topics:

How the Recovery Point Objective Affects Replication Scheduling

How the 5 Minute Recovery Point Objective Works

How Retention Policy Works

Replicating a Virtual Machine and Enabling Multiple Point in Time Instances

Using vSphere Replication with Virtual SAN Storage

Using vSphere Replication with vSphere Storage DRS

VMware, Inc.

Using VMware vSphere Replication

How vSphere Replication Synchronizes Data Between vCenter Server Sites During Initial

Configuration

Replicating Virtual Machines Using Replication Seeds

Replicating a Virtual Machine in a Single vCenter Server Instance

Best Practices For Using and Configuring vSphere Replication

Configure Replication for a Single Virtual Machine to vCenter Server

Configure Replication for Multiple Virtual Machines to vCenter Server

Move a Replication to a New vSphere Replication Server

Stop Replicating a Virtual Machine

Reconfiguring Replications

How the Recovery Point Objective Aects Replication Scheduling

When you set a Recovery Point Objective (RPO) value during replication configuration, you determine the

maximum data loss that you can tolerate.

The RPO value affects replication scheduling, but vSphere Replication does not adhere to a strict

replication schedule. For example, when you set the RPO to 15 minutes, you instruct vSphere Replication

that you can tolerate losing the data for up to 15 minutes. This does not mean that data is replicated

every 15 minutes.

If you set an RPO of x minutes, and the RPO is not violated, the latest available replication instance can

never reflect a state that is older than x minutes. A replication instance reflects the state of a virtual

machine at the time the synchronization starts.

Assume that during replication configuration you set the RPO to 15 minutes. If the synchronization starts

at 12:00 and it takes five minutes to transfer to the target site, the instance becomes available on the

target site at 12:05, but it reflects the state of the virtual machine at 12:00. The next synchronization can

start no later than 12:10. This replication instance is then available at 12:15 when the first replication

instance that started at 12:00 expires.

If you set the RPO to 15 minutes and the replication takes 7.5 minutes to transfer an instance,

vSphere Replication transfers an instance all the time. If the replication takes more than 7.5 minutes, the

replication encounters periodic RPO violations. For example, if the replication starts at 12:00 and takes 10

minutes to transfer an instance, the replication finishes at 12:10. You can start another replication

immediately, but it finishes at 12:20. During the time interval 12:15-12:20, an RPO violation occurs

because the latest available instance started at 12:00 and is too old.

The replication scheduler tries to satisfy these constraints by overlapping replications to optimize

bandwidth use and might start replications for some virtual machines earlier than expected.

To determine the replication transfer time, the replication scheduler uses the duration of the last few

instances to estimate the next one.

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How the 5 Minute Recovery Point Objective Works

You can use the 5 minute Recovery Point Objective (RPO) if the target and the source sites use VMFS

6.0, VMFS 5.x, NFS 4.1, NFS 3, VVOL, or Virtual SAN 6.0 storage and later.

vSphere Replication 6.5 displays the 5 minute RPO setting when the target and the source site use

VMFS 6.0, VMFS 5.x, NFS 4.1, NFS 3, VVOL, or Virtual SAN 6.0 storage and later.

You can use the 5 minute RPO setting if you are using different datastore types between the source and

the target site.

The 5 minute RPO can be applied to a maximum of 100 VMs on VMFS 6.0, VMFS 5.x, NFS 4.1, NFS 3,

and Virtual SAN 6.0 storage and later. The maximum for VVOL datastore is 50 VMs.

Note If you select the OS quiescing option while configuring replication, you cannot use an RPO value

lower than 15 minutes.

How Retention Policy Works

When you configure a replication, you can enable the retention of up to 24 VM replica instances from

Multiple Points in Time (MPIT).

For example, you can configure the retention of 3 instances per day for the last 5 days.

After you recover a replicated virtual machine, the retained replicas appear as snapshots of the virtual

machine in the vSphere Web Client. The list of snapshots includes the retained instances according to the

retention policy that you set, and the latest instance. By the example above, the list will contain 15

snapshots and the latest saved instance of the virtual machine, or a total of 16 snapshots. You can use

the snapshots to revert to an earlier state of the recovered virtual machine.

Administrators cannot configure the precise time when replica instances are created, because the

retention policy is not directly related to replication schedule and RPO. As a consequence, replications

with the same retention policy might not result in replicas retained at the same time instants.

RPO Without Retention Policy

By default, vSphere Replication is configured to a 4-hour RPO. This means that the latest available

replica instance can never reflect a state of the virtual machine that is older than 4 hours. You can adjust

the RPO interval when you configure or reconfigure a replication.

When the age of the latest replication instance approaches the RPO interval, vSphere Replication starts a

sync operation to create a new instance on the target site. The replication instance reflects the state of

the virtual machine at the time the synchronisation starts. If no retention policy is configured, when the

new instance is created, the previous instance expires and the vSphere Replication Server deletes it.

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How RPO and the Retention Policy Combine

To save some of the replica instances that are created during RPO synchronisations, you can configure

vSphere Replication to keep up to 24 instances per replication. The exact instances that

vSphere Replication keeps are determined by applying a specific algorithm. Using this algorithm, the

vSphere Replication Server tries to match each instance to a slot of the retention policy. Instances that do

not match any slot expire and are deleted. If a slot contains more than one instance, the instances that do

not match the retention criteria are also deleted. vSphere Replication always keeps the latest created

instance and it is not taken into account when determining the number of instances to keep.

When the age of the latest instance approaches the RPO interval, vSphere Replication starts creating a

new replica instance. The start time of the sync operation is the time of the new instance. When the sync

operation completes, vSphere Replication assesses the existing replica instances to determine which

ones to keep:

1 The granularity of the retention policy is determined based on the replication settings. For example, if

you configured vSphere Replication to keep 3 instances for the last 1 day, it means that you want to

keep 3 replica instances that are relatively evenly distributed over 24 hours. This equals

approximately 1 instance in a 8-hour interval, or the granularity of this retention policy is 8 hours.

2 The time of the last saved instance is rounded down to the nearest slot time. If the granularity is 8

hours, the slot times are 0:00, 8:00, and 16:00.

3 The instances that are between the nearest slot time and the last saved instance are traversed. Let

us assume that the time of the last saved instance is 10:55. Following our example, the nearest slot

time is 8:00 o'clock. Let us also assume that the RPO is 1 hour, and each sync operation takes 5

minutes to complete. Between 8:00 o'clock and 10:55, the slot contains an 8:55 instance, and a 9:55

instance.

4 The earliest instance that is newer than the nearest slot time is saved, and the rest of the instances in

this slot are deleted, except for the latest created instance that vSphere Replication always keeps.

Following our example, the 8:55 instance is saved, and the 9:55 instance is deleted. The 10:55

instance is the latest created instance, so it is also saved.

5 The slot time is decremented by the granularity of the retention policy and a check is performed for

the earliest instance between the beginning of the current slot and the beginning of the previous slot.

If the slot contains expiring instances, they are deleted.

6 The number of slots that contain saved instances is analyzed. If the number of slots with saved

instances is higher than the number of slots determined by the retention policy, the oldest saved

instance expires and is deleted. The last saved instance is not included in this count. In our example,

if we had an instance saved for the interval 8:00 - 16:00 o'clock of the previous day, that instance

would be deleted.

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vSphere Web Client

VR Appliance

VM VM VM

t3t2

vSphere Web Client

VR Appliance

Replication

Source Site

Target Site

Using VMware vSphere Replication

The number of replication instances that vSphere Replication keeps depends on the configured retention

policy, but also requires that the RPO period is short enough for these instances to be created. Because

vSphere Replication does not check whether the RPO settings will create enough instances to keep, and

does not display a warning message if the instances are not enough, you must ensure that you set

vSphere Replication to create the instances that you want to keep. For example, if you set

vSphere Replication to keep 6 replication instances per day, the RPO period should not exceed 4 hours,

so that vSphere Replication can create 6 instances in 24 hours.

Replicating a Virtual Machine and Enabling Multiple Point in Time Instances

You can recover virtual machines at specific points in time (PIT) such as the last known consistent state.

When you configure replication of a virtual machine, you can enable multiple point in time (PIT) instances

in the recovery settings in the Configure Replication wizard. vSphere Replication retains a number of

snapshot instances of the virtual machine on the target site based on the retention policy that you specify.

vSphere Replication supports a maximum of 24 snapshot instances. After you recover a virtual machine,

you can revert it to a specific snapshot.

During replication, vSphere Replication replicates all aspects of the virtual machine to the target site,

including any potential viruses and corrupted applications. If a virtual machine suffers from a virus or

corruption and you have configured vSphere Replication to keep PIT snapshots, you can recover the

virtual machine and then revert it to a snapshot of the virtual machine in its uncorrupted state.

You can also use the PIT instances to recover the last known good state of a database.

Note vSphere Replication does not replicate virtual machine snapshots.

Figure 2‑1. Recovering a Virtual Machine at Points in Time (PIT)

Using vSphere Replication with Virtual SAN Storage

You can use VMware Virtual SAN datastores as target datastores when configuring replications. Follow

the guidelines when using vSphere Replication with Virtual SAN storage.

Note VMware Virtual SAN is a fully supported feature of vSphere 5.5 Update 1 and later.

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Using VMware vSphere Replication

Because user-friendly names of Virtual SAN datastores might change and cause errors during replication

or recovery operations, vSphere Replication automatically replaces the user-friendly name of a datastore

with its UUID, which is constant. Therefore, the UUID is displayed everywhere in the vSphere Replication

user interface, though you selected a human-readable name during replication configuration.

Limits of Using vSphere Replication with Virtual SAN Storage

For reasons of load and I/O latency, Virtual SAN storage is subject to limits in terms of the numbers of

hosts that you can include in a Virtual SAN cluster and the number of virtual machines that you can run

on each host. See the Limits section in the VMware Virtual SAN Design and Sizing Guide at

http://www.vmware.com/products/virtual-san/resources.html.

Using vSphere Replication adds to the load on the storage. Every virtual machine generates regular read

and write operations. Configuring replications on those virtual machines adds another read operation to

the regular read and write operations, which increases the I/O latency on the storage. The precise

number of virtual machines that you can replicate to Virtual SAN storage by using vSphere Replication

depends on your infrastructure. If you notice slower response times when you configure replications for

virtual machines in Virtual SAN storage, monitor the I/O latency of the Virtual SAN infrastructure.

Potentially, reduce the number of virtual machines that you replicate in the Virtual SAN datastore.

Note When you stop a replication, vSphere Replication does not delete the replica directory at the target

datastore. As a result, stale directories remain on VMFS and NFS target datastores, and unused

namespaces remain on Virtual SAN and Virtual Volume target datastores. Because the maximum number

of directories and namespaces on a datastore is limited, you must manually clean them up to free

resources on the datastore. See Clean Up the Target Datastore After You Stop a Replication.

Retaining Point-in-Time Snapshots when Using Virtual SAN Storage

Virtual SAN storage stores virtual machine disk files as a set of objects and components. Each disk object

in Virtual SAN storage has mirror and witness objects. In the default Virtual SAN storage policy, a disk

object has 2 mirrors and one witness. The number of mirror components is determined by the size of the

virtual machine disk and the number of failures to tolerate that you set in your Virtual SAN storage policy.

A mirror object is divided into components of a maximum size of 256 GB each.

If a virtual machine has one 256 GB disk and you use the default Virtual SAN storage policy, the disk

object will have 2 mirror components of 256 GB each and 1 witness, to make a total of 3 components.

If a virtual machine has one 512 GB disk and you use the default Virtual SAN storage policy, the disk

object will have 4 mirror components of 256 GB each and 1 witness, to make a total of 5 components.

See the VMware Virtual SAN Design and Sizing Guide at

http://www.vmware.com/products/virtual-san/resources.html for explanations of objects, components,

mirrors, witnesses, and Virtual SAN storage policies.

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Using VMware vSphere Replication

If you enable multiple point-in-time (PIT) snapshots, you must make allowances for the additional

components that each snapshot creates in the Virtual SAN storage, based on the number of disks per

virtual machine, the size of the disks, the number of PIT snapshots to retain, and the number of failures to

tolerate. When retaining PIT snapshots and using Virtual SAN storage, you must calculate the number of

extra components that you require for each virtual machine:

Number of disks x number of PIT snapshots x number of mirror and witness components

Examples of using this formula demonstrate that retaining PIT snapshots rapidly increases the number of

components in the Virtual SAN storage for every virtual machine that you configure for

vSphere Replication:

You have a virtual machine with two 256 GB disks for which you retain 10 MPIT snapshots, and you

set the default Virtual SAN storage policy:

2 (number of disks) x 10 (number of PIT snapshots) x 3 (2 mirror components + 1 witness) = 60

components for this one virtual machine.

You have a virtual machine with two 512 GB disks for which you retain 10 PIT snapshots, and you set

the default Virtual SAN storage policy:

2 (number of disks) x 10 (number of PIT snapshots) x 5 (4 mirror components of 256 GB each + 1

witness) = 100 components for this one virtual machine.

The number of PIT snapshots that you retain can increase I/O latency on the Virtual SAN storage.

Using vSphere Replication with vSphere Storage DRS

vSphere Replication can operate with target sites that have VMware vSphere® Storage DRS™ enabled.

Storage DRS can detect the data that vSphere Replication copies on the target site and can move

replications without affecting the replication process.

How vSphere Replication Synchronizes Data Between vCenter Server Sites During Initial Conﬁguration

When you configure a virtual machine for replication, vSphere Replication starts an initial configuration

task during which a replica virtual machine is created on the target site, and data synchronization occurs

between the source and the target vCenter Server site.

The speed of data synchronization depends on the availability of information about block allocation of the

VMDK files. vSphere Replication uses this information to find empty regions of the disks and accelerate

the sync operations by skipping these regions. The speed of data synchronization also depends on the

site for which block allocation information is available.

If the allocation information is available at both sites, data synchronization occurs at the highest

possible speed.

If the allocation information is available only at the source or the target site, vSphere Replication skips

the empty regions on the VMDK disks at that site, but processes the entire disk at the site where

allocation information is not available. Therefore, data synchronization is slower.

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Using VMware vSphere Replication

If the allocation information is not available at either site, data synchronization is done by comparing

all blocks between the source site and the target site, even if many of the blocks have not been

allocated on the disk by the guest OS. This is the slowest method for data synchronization.

Note The availability of block allocation information has little effect on the speed of data synchronization

for VMDK disks that are almost full.

Factors That Aect the Availability of Block Allocation Information

The availability of allocation information and the degree to which vSphere Replication can use it to

accelerate data synchronization depend on the ESXi versions, the vSphere Replication Management

server versions, the type of VMDK disks, and the type of volumes on which the disks reside.

Product Versions at the

Source and the Target

Site

The Type of the

Datastore

The acceleration of initial synchronization is supported only on ESXi hosts

6.0.x or later.

If the ESXi and the vSphere Replication Server on the source site are 6.x or

later, but the vSphere Replication Server or the hosts at the target site are

not 6.x or later, the allocation information will be available only on the

source site.

If the vSphere Replication Management servers at the source and at the

target site are both 6.x, but one or more ESXi hosts at the target site are

not 6.0 or later, if the vSphere Replication Management server selects a

target host that is not 6.0 or later, there will be no allocation information

available on the target site.

Note Because vSphere Replication Management server 6.x cannot select

only ESXi 6.0 hosts for the initial synchronization, the acceleration of the

operations might vary depending on the selected host. To achieve

maximum acceleration, all ESXi hosts at the target site that act as storage

servers for vSphere Replication should be ESXi 6.0 or later.

Disks on VMFS or VSAN datastores provide full allocation information.

NFS datastores cannot provide allocation information for the disks that are

located on them.

Note Replication disks on the source and the target site can be on

different datastore types. The acceleration of the initial synchronization

depends on whether both sites can provide allocation information, or only

one site. If none of the sites can provide allocation information, no

acceleration occurs.

The Type of Virtual Disk Lazy zeroed thick disks, thin disks, and vSAN sparse disks, Space-Efficient

sparse disks, and VMDK sparse snapshots provide allocation information.

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Using VMware vSphere Replication

Eager zeroed thick disks do not provide allocation information.

Virtual disks that are based on VVOLs are native to the volume.

vSphere Replication 6.x can get allocation information from them only when

they are on the target site. For this reason, the acceleration of the initial

synchronization will be partial.

Replicating Virtual Machines Using Replication Seeds

To reduce the network traffic that is generated by data transfer during the initial full synchronization,

vSphere Replication allows you to copy virtual disk files or use files that already exist in the target

datastore, and point those as replication seeds when you configure a replication.

vSphere Replication compares the differences on the source and target site, and replicates only the

changed blocks.

When, during replication configuration, you select a target datastore for the virtual machine,

vSphere Replication looks for a disk with the same filename in the target datastore. If a file with the same

name exists, vSphere Replication prompts you with a warning and offers you the option to use the

existing disk file as a seed for the replication. If you accept the option, after the virtual machine replication

is fully configured and enabled, vSphere Replication compares the differences and replicates only the

changed blocks. If you do not accept the prompt, you must change the target location for your replication.

Note If you plan to copy files from the source to the target datastore, the source virtual machine must be

powered off before downloading the vmdk files that will be used as seeds for the replication.

Replicating a Virtual Machine in a Single vCenter Server Instance

You can use vSphere Replication to replicate a virtual machine in a single vCenter Server even if the

vCenter Server instance has only one host in its inventory.

When you configure replication in a single vCenter Server instance, you can select the source site as the

target site for replication. You then configure replication in the same way as for an infrastructure with a

source and a target site. For example, you can replicate a virtual machine to a different datastore

attached to the same host or another host. vSphere Replication prevents you from using the source or

replicated virtual machine's vmdk files as the target of the replication.

The virtual machine name must be unique in the same folder in the vCenter Server inventory. In the

recovery wizard, vSphere Replication does not allow you to select a folder if there is already a virtual

machine with the same name registered to it. During recovery if there is a virtual machine with the same

name, you might see an error message. See Error Recovering Virtual Machine in a Single vCenter Server

Instance for more information.

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Using VMware vSphere Replication

Best Practices For Using and Conﬁguring vSphere Replication

Best practices for using and configuring vSphere Replication can prevent your environment from possible

issues during replication.

Setting the Optimal Recovering Point Objective (RPO) Time

The replication of several thousand virtual machines (VMs) is a bandwidth consuming process.

vSphere Replication lets you set the RPO to 15 minutes, but you must estimate the optimal RPO time to

save bandwidth for replication and to cover your business requirements for protection of your VMs. For

example, if your business requires replication of 2,000 VMs with an 8 hour RPO, set the RPO time to 8

hours to meet the business needs and save bandwidth. For more details, see Calculate Bandwidth for

vSphere Replication in the vSphere Replication Installation and Configuration guide.

Using Multiple Point in Time (MPIT) Recovery

Each point in time snapshot consumes storage. The amount consumed depends on the data change rate

in the VM. When you set multiple point in time instances for replication of a VM between two

vCenter Server sites, vSphere Replication presents the retained instances as standard snapshots after

recovery. The time required to consolidate snapshots after recovery, increases with the number of

snapshots.

Although vSphere Replication supports up to 24 recovery points, you must set the MPIT to the lowest

number of recovery points that meets your business requirements. For example, if the business

requirement is for 10 recovery points, you must set up vSphere Replication to save only 10 snapshots.

You can set up two recovery points per day for the last five days. As a result, the consumed storage and

the time needed to consolidate the snapshots after recovery are less than if you use the maximum

number of recovery points.

Conﬁguring Quiescing

For VMs with high levels of storage I/O, quiescing of the file system and applications can take several

minutes and impact the performance of the VM . When quiescing a file system and applications for

Windows VMs, vSphere Replication requires a regular VM snapshot before replication. When you

estimate the RPO time, consider the time and resource consumption for the quiescing and for the

consolidation of the snapshots. For example, if you configure replication of a Windows VM with an RPO

of 15 minutes and quiescing is enabled, vSphere Replication generates a VM snapshot and consolidates

it every 15 minutes.

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Using VMware vSphere Replication

Conﬁguring Replication Seeds

You can copy virtual disk files of source VMs to the target location and use these files as replication

seeds. By using replication seeds, vSphere Replication reduces the amount of time and network

bandwidth required for the initial full sync process. The UUID of the source and target VMDK files must

match for the replication to be successful and to prevent unintentional overwrites of disk files that belong

to other VMs at the target location.

Monitoring a Datastore on the Target Site

vSphere Replication requires enough disk space at the target site to replicate a VM. If the available space

is not enough to save the replication files, the replication might fail. You can create an alarm that alerts

you about insufficient storage capacity at the target site.

Conﬁgure Replication for a Single Virtual Machine to vCenter Server

vSphere Replication can protect individual virtual machines and their virtual disks by replicating them from

one vCenter Server instance to another.

This procedure is for configuring replications to a target vCenter Server. To configure a replication to a

cloud provider, see vSphere Replication for Disaster Recovery to the Cloud.

When you configure replication, you set a recovery point objective (RPO) to determine the maximum data

loss that you can tolerate. For example, an RPO of 1 hour seeks to ensure that a virtual machine loses

the data for no more than 1 hour during the recovery. For smaller RPO values, less data is lost in a

recovery, but more network bandwidth is consumed keeping the replica up to date. The RPO value affects

replication scheduling, but vSphere Replication does not adhere to a strict replication schedule. See How

the Recovery Point Objective Affects Replication Scheduling and How the 5 Minute Recovery Point

Objective Works.

Every time that a virtual machine reaches its RPO target, vSphere Replication records approximately

3800 bytes of data in the vCenter Server events database. If you set a low RPO period, this can quickly

create a large volume of data in the database. To reduce the volume of data that is kept in the

vCenter Server events database, limit the number of days that vCenter Server retains event data. See

Configure Database Retention Policy in the vCenter Server and Host Management Guide. Alternatively,

set a higher RPO value.

vSphere Replication guarantees crash consistency amongst all the disks that belong to a virtual machine.

If you use quiescing, you might obtain a higher level of consistency. The available quiescing types are

determined by the operating system of the virtual machine. See Interoperability Pages for vSphere

Replication 6.5 for quiescing support for Windows and Linux virtual machines.

You can configure virtual machines to replicate from and to Virtual SAN datastores. See Using vSphere

Replication with Virtual SAN Storage for the limitations when using vSphere Replication with Virtual SAN.

Note VMware Virtual SAN is a fully supported feature of vSphere 5.5 Update 1 and later.

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Using VMware vSphere Replication

Prerequisites

Verify that the vSphere Replication appliance is deployed at the source and the target sites.

To enable the quiescing of virtual machines that run Linux guest OS, install the latest version of

VMware Tools on each Linux machine that you plan to replicate.

Procedure

1 On the vSphere Web Client Home page, click vSphere Replication.

2 Select a vCenter Server and click the VMs tab.

The Virtual Machines tab lists the virtual machines.

3 Right-click the virtual machine and select All vSphere Replication Actions > Configure replication.

4 Select Replicate to a vCenter Server.

5 Select the target site.

If you want to configure a replication to a local target site, select the target site from the list and

click Next.

If the source and target sites are not connected, the connection between the sites is configured

when you click Next.

If you want to configure a replication to a remote target site, and the source and target sites are

connected, select the target site from the list and click Next.

If you want to configure a replication to a remote target site, and the source and target sites are

not connected, click Add Remote Site), enter the IP address or host name of the server where

the target PSC runs, and provide the credentials of a user that has the VRM remote.Manage

VRM privilege assigned. When the user is authenticated with the target site, all vCenter Server

instances on which the vSphere Replication Management Server is registered with the Lookup

Service appear in the list of target sites. Select the target site from the list and click OK and Next.

6 Accept the automatic assignment of a vSphere Replication server or select a particular server on the

target site and click Next.

7 On the Target Location page, click Edit to select or change the target location datastore.

Optionally, you can select the virtual machine storage policy.

8 (Optional) To configure the replication of individual disks, click the name of the source virtual

machine.

The list of disks on the source virtual machine expands.

For each disk, you can select the virtual format, storage policy, and a datastore where it is replicated.

You can disable the replication of a disk by clicking Disable in its Replication Enabled row.

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9 (Optional) On the Replication options page, select the quiescing method for the guest operating

system of the source virtual machine.

Note Quiescing options are available only for virtual machines that support quiescing.

vSphere Replication does not support VSS quiescing on Virtual Volumes.

10 (Optional) Select Enable network compression for VR data.

Compressing the replication data that is transferred through the network saves network bandwidth

and might help reduce the amount of buffer memory used on the vSphere Replication server.

However, compressing and decompressing data requires more CPU resources on both the source

site and the server that manages the target datastore.

11 On the Recovery settings page, use the RPO slider or the time spinners to set the acceptable period

for which data can be lost in the case of a site failure.

The available RPO range is from 5 minutes to 24 hours for target and source sites.

12 (Optional) To save multiple replication instances that can be converted to snapshots of the source

virtual machine during recovery, select Enable in the Point in time instances pane, and adjust the

number of instances to keep.

Note You can keep up to 24 instances for a virtual machine. This means that if you configure

vSphere Replication to keep 6 replication instances per day, the maximum number of days you can

set is 4 days.

The number of replication instances that vSphere Replication keeps depends on the configured

retention policy, but also requires that the RPO period is short enough for these instances to be

created. Because vSphere Replication does not check whether the RPO settings will create enough

instances to keep, and does not display a warning message if the instances are not enough, you

must ensure that you set vSphere Replication to create the instances that you want to keep. For

example, if you set vSphere Replication to keep 6 replication instances per day, the RPO period

should not exceed 4 hours, so that vSphere Replication can create 6 instances in 24 hours.

13 Click Next.

14 On the Ready to complete page, review the replication settings, and click Finish.

vSphere Replication starts an initial full synchronization of the virtual machine files to the designated

datastore on the target site.

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Conﬁgure Replication for Multiple Virtual Machines to vCenter Server

You can configure replication for multiple virtual machines from one vCenter Server instance to another

by using the Multi-VM Configure Replication wizard.

When you configure replication, you set a recovery point objective (RPO) to determine the maximum data

loss that you can tolerate. For example, an RPO of 1 hour seeks to ensure that a virtual machine loses

the data for no more than 1 hour during the recovery. For smaller RPO values, less data is lost in a

recovery, but more network bandwidth is consumed keeping the replica up to date. The RPO value affects

replication scheduling, but vSphere Replication does not adhere to a strict replication schedule. See How

the Recovery Point Objective Affects Replication Scheduling and How the 5 Minute Recovery Point

Objective Works.

Every time that a virtual machine reaches its RPO target, vSphere Replication records approximately

3800 bytes of data in the vCenter Server events database. If you set a low RPO period, this can quickly

create a large volume of data in the database. To reduce the volume of data that is kept in the

vCenter Server events database, limit the number of days that vCenter Server retains event data. See

Configure Database Retention Policy in the vCenter Server and Host Management Guide. Alternatively,

set a higher RPO value.

vSphere Replication guarantees crash consistency amongst all the disks that belong to a virtual machine.

If you use quiescing, you might obtain a higher level of consistency. The available quiescing types are

determined by the operating system of the virtual machine. See Interoperability Pages for vSphere

Replication 6.5 for quiescing support for Windows and Linux virtual machines.

You can configure virtual machines to replicate from and to Virtual SAN datastores. See Using vSphere

Replication with Virtual SAN Storage for the limitations when using vSphere Replication with Virtual SAN.

Note VMware Virtual SAN is a fully supported feature of vSphere 5.5 Update 1 and later.

Configuring vSphere Replication on a large number of virtual machines simultaneously when using Virtual

SAN storage can cause the initial full synchronization of the virtual machine files to run very slowly. Initial

full synchronization operations generate heavy I/O traffic, and configuring too many replications at the

same time can overload the Virtual SAN storage. Configure vSphere Replication in batches of a

maximum of 30 virtual machines at a time.

Prerequisites

Verify that the vSphere Replication appliance is deployed at the source and the target sites.

To enable the quiescing of virtual machines that run Linux guest OS, install the latest version of

VMware Tools on each Linux machine that you plan to replicate.

Procedure

1 On the vSphere Web Client Home page, click vSphere Replication.

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2 Select a vCenter Server and click the VMs tab.

The Virtual Machines tab lists the virtual machines.

3 Select the virtual machines to replicate by using the Ctrl or Shift keys.

4 Right-click the virtual machines and select All vSphere Replication Actions > Configure

replication.

The virtual machines pass a validation check before they can be configured for replication.

5 Click Next.

6 Select Replicate to a vCenter Server.

7 Select the target site.