vSphere Replication can protect one or more virtual machines and their virtual disks by replicating them from one vCenter Server instance to another.
When you configure a 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 among 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 Compatibility Matrices for vSphere Replication 8.3 for quiescing support for Windows and Linux virtual machines.
You can configure virtual machines to replicate from and to vSAN datastores. See Using vSphere Replication with vSAN Storage for the limitations when using vSphere Replication with vSAN.
- 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.
- If you want to replicate an encrypted VM or to enable the network encryption of a replication, verify that your environment meets the requirements. See Replicating Encrypted Virtual Machines.
- Log in to the vSphere Client or vSphere Web Client.
- On the home page, click Site Recovery and click Open Site Recovery.
- On the Site Recovery home page, select a site pair and click View Details.
- Click the Replications tab, select Outgoing or Incoming, and click the Create new replication icon.
- On the Virtual machines page of the Configure Replication wizard, select the virtual machines you want to replicate and click Next.
- Accept the automatic assignment of a vSphere Replication server or select a particular server on the target site and click Next.
- On the Target datastore page, select a datastore on which to replicate files.
When replicating multiple virtual machines, you can configure a different target datastore for each virtual machine.
- (Optional) Select the Select seeds check box.
Replication seeds can reduce the network traffic during the initial full synchronization, but unintended use of replication seeds might lead to data loss.
- (Optional) Select or deselect the Auto-include new disks in replication check box.
Keep the check box selected to automatically include new disks in the replication, with the same replication configuration as the source virtual machine. Disk format for the automatically included disks is determined the following way: If all replicated disks use the Same as source format, the Same as source format is applied to the automatically included disks. If that is not the case, but all replicated disks use the same format, for example Thin provision, the same format ( Thin provision) is applied to the automatically included disks. If all replicated disks use different formats, the Same as source format is applied to the automatically included disks.If you enable the Configure datastore per disk view, you can enable or disable the automatic replication of new disks by toggling the New Hard disk switch.
- Click Next.
- (Optional) On the Select seed page, review the suggested replication seeds and change them if necessary.
You can select seed files for each virtual machine disk and search for seeds by using the dropdown menu and clicking Browse.The replica files for the disk are written in the seeds file directory.
- Select the The selected seeds are correct check box and click Next.
- On the Replication settings page, use the RPO slider to set the acceptable period for which data can be lost if a site failure occurs.
The available RPO range is from 5 minutes to 24 hours.
- (Optional) To save multiple replication instances that can be converted to snapshots of the source virtual machine during recovery, select Enable point in time instances and adjust the number of instances to keep.
Note: You can keep up to 24 instances for a virtual machine. For example, 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 verify 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 must not exceed 4 hours, so that vSphere Replication can create 6 instances in 24 hours.
- (Optional) Enable quiescing 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.
- (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.
- (Optional) Enable the network encryption of the replication traffic.
If you configure a replication of an encrypted VM, this option is automatically turned on and cannot be disabled.
- 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.