vRanger 7.8.1 - User Guide

Differential replication

Differential replication

In differential replication, vRanger compares the data blocks on the source VM to a data map to identify blocks that have changed since the last replication pass. These changed blocks are sent to the target VM and committed to disk, and the data map is updated to reflect the current state of both VMs.

When using differential replication, consider the following:

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During the first replication pass, the entire VM image needs to be sent to the target VM. During subsequent replication passes, only changed data is sent. To avoid sending the entire VM image over the network, consider pre-seeding the target VM. For more information, see Pre-seeding replication jobs

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After the first replication pass, the source VM is scanned and the blocks are compared to the most recent data map. This scanning process can take an average of one minute per gigabyte of hard drive space; however, the actual speed depends on the underlying hardware being used. While only the changed data is sent to the target VM, the entire hard drive must be scanned. When configuring differential replication jobs for large VMs, take this scanning time into account. To eliminate the need for scanning, use replication with CBT if at all possible.

Configuring transport failover options

Configuring transport failover options

Replication transport actions occur through HotAdd — LAN-free or network. If one transport method is not available, vRanger attempts to perform the replication task using one of the other transport methods. You may configure the order in which vRanger attempts the transport options with the Transport Failover node of the Configuration Options page. For VMware® ESXi™ hosts, configure the transport order to VA-based HotAdd > VA-based Network.

Pre-seeding replication jobs

Pre-seeding replication jobs

vRanger replication is intended to replicate changes from a source VM to a remote target. It is often not practical to perform the first replication pass — which sends the full VM) to a remote site over a WAN link. You may use vRanger to “seed” a replication job locally to reduce the amount of data sent over the WAN.

To pre-seed replication jobs, complete the following tasks:

•	Backing up the source VM

•	Replicating the changes

Backing up the source VM

Complete the steps in the following procedure to back up the source VM.

To back up the source VM:

1	If vRanger is not already installed, do so.

2	Select the VM you want to get to the disaster recovery (DR) site, and create a Full backup job.

3	Back up the VM locally.

4	Copy the backup savepoint, and move it to the DR site.

You can complete this step by shipping a USB drive or some other media containing the backup archive.

Savepoints are named using a VMname_date_time_UUID format. Copy the entire directory, which contains a .var file and two .metadata files, for the savepoint in question.

5	Using the Restore from Manifest function documented in Performing a full restore from manifest for VMware VMs, restore the backup to the target VMware® ESXi™ Server at the DR site.

Replicating the changes

Complete the steps in the following procedure to replicate the changes made to the VM.

To replicate the changes:

1	Start vRanger, and expand the host where the source VM is located.

2	Right-click the VM, and select Replicate <VM name>.

3	Configure a replication job with the preferred options.

4	When selecting the target host, select the host on the target side to which the source VM has been restored.

 

NOTE: When selecting the target VM name, ensure that you are using the same name as the source VM. vRanger appends “_VzReplicate” to the VM name on the target side.

5	In the Select Target Host dialog box, next to Preseed VM UUID, click the browse button, and select the pre-seeded VM.

6	When configuring the primary datastore, ensure that it is the same datastore as the restored VM, and click Finish.

7	Run the replication job.

Only the data changes pass over the WAN as opposed to the full VM.

Creating a replication job

Creating a replication job

vRanger uses a simple wizard to guide you through the process of creating a replication job. At a high level, the process includes the following steps. Each of the steps is explained in more detail in the topics that follow.

To create a replication job, complete the following tasks:

•	Selecting the source VM

•	Selecting a target host

•	Selecting the replication mode

•	Selecting replication network mapping

•	Selecting hard disks

•	Selecting replication options

•	Setting the recurrence schedule

•	Configuring email notifications

•	Starting the replication job

Selecting the source VM

Complete the steps in the following procedure to select the source VM.

To select the source VM:

1	Click My Inventory.

2	Right-click the VM you want to replicate, and select Replicate <VMname>.

 

NOTE: If there is no VA provided for the selected VM, the Virtual Appliance Not Found window notifies you that the replication job is going to fail without a VA. For more information, see Understanding the vRanger virtual appliance (VA).

3	Enter the Job Name and Job Description, and click Next.

Selecting a target host

On the Select Target Host page, complete the following steps to select a target host.

To select a target host:

1	Do one of the following:

▪	Choose a Target Host from the list, and click Next.

▪

If you have pre-seeded the VM on the target host, select the host on the target side to which the source VM has been restored. For more information, see Pre-seeding replication jobs. When selecting the target VM name, ensure that you are using the same name as the source VM. vRanger appends “_VzReplicate” to the VM name on the target side.

2	[Optional] In the Select Target Host dialog box, next to Preseed VM UUID, click the browse button, and select the pre-seeded VM.

 

IMPORTANT: After a replication job has been saved, you cannot change the target host. If you want to replicate to a different host, you may either use VMware vSphere® vMotion® to migrate the VM to the preferred host, or create a replication job for the preferred target. If you vMotion the VM, the existing replication job should identify the change in host and adjust automatically.

Selecting the replication mode

On the Replication Mode page, you can select between differential replication and hybrid replication. For more information, see Replication modes.

To select the replication mode:

1	On the Replication Mode page, under Replication Type, select Differential Replication.

 

NOTE: Hybrid replication is not supported when replicating to or from VMware® ESXi™. This feature is deprecated for vRanger 7.2 and later.

2	Click Next.

Selecting replication network mapping

On the Replication Network Mapping page, you specify the network on the target host to which the VM nics should connect.

To select replication network mapping:

1	Select the Network Mapping you want to use for this job.

2	Click Next.

Selecting hard disks

The Select which Hard Disk(s) to replicate page lets you include or exclude specific disks from replication.

To select hard disks:

1	Select the hard disks you want to replicate.

You may select a Primary Datastore, which is used as the default for all disks in this job, letting you configure only the exceptions.

2	In the Target Datastore column, verify that the Primary Datastore has been populated.

3	If you want the disk to replicate to a different datastore, click the browse button (…) next to the Target Datastore selection.

4	On the Select Primary Storage page, review the list of datastores.

This page lists all datastores associated with the selected host. Datastores are first grouped based on whether they are governed by a storage policy. Datastores are also grouped based on whether they reside in a DRS cluster. You can expand or collapse groups as needed.

 

NOTE: VVol datastores only support thin disks. If your VM resided on a thick disk during the backup and you select a VVol datastore for the replicated VM, vRanger automatically converts the setup to thin disks.

5	Select the applicable datastore, and click OK.

6	When the Select which Hard Disk(s) to replicate page appears, click Next.

Selecting replication options

The Replication Options page lets you configure additional operations performed during the replication job. You may also view the transport failover preferences, and modify them as needed.

To select replication options:

1	Configure the replication options, using the following table for guidance.

 

Option	Description
Check destination for free space.	This option prompts vRanger to check the destination location to ensure that there is enough space available for the replica VM.
Update notes with latest replication results.	If this flag is selected, vRanger updates the VM Notes in VC with the most recent replication task status. NOTE: vRanger maintains the existing VM notes in VMware® vCenter™, appending the replication status to the end.
Enable guest quiescing.	This option enables the VMware® Tools when creating a snapshot. Use this flag if you are replicating a database server. During this process, vRanger freezes or pauses writes on supported applications to provide a consistent image of VSS-enabled databases. For more information, see Physical backup transport options.
Enable Active Block Mapping (ABM).	Selecting this option enables ABM, which lets vRanger skip data that recognized as removed on Windows® NTFS — including junk data in recycle bin. NOTE: With this option enabled, junk data in recycle bin and deleted data on the VM are not replicated. The following ABM settings options are also available: • Do not include the Windows page file. • Do not include the Windows hibernation file.

2	Verify your Transport Failover preference.

If you want to change the Transport Failover order, click Modify. For more information, see Configuring transport failover options.

3	Click Next.