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 6.1 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.
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.
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.
- On the vSphere Web Client Home page, click vSphere Replication.
- Select a vCenter Server and in the left pane, double-click Virtual Machines.
On the Related Objects tab, the Virtual Machines tab lists the virtual machines.
- Select the virtual machines to replicate by using the Ctrl or Shift keys.
- Right-click the virtual machines and select
The virtual machines pass a validation check before they can be configured for replication.
- Click Next.
- Select Replicate to a vCenter Server.
- 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 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.
- Accept the automatic assignment of a vSphere Replication server or select a particular server on the target site and click Next.
- On the Target Location page, click Edit to select or change the target location datastore.
Optionally, you can select the virtual machine storage policy.
- (Optional) On the Replication options page, select the quiescing method for the guest operating system of the source virtual machine.
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.
- 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 using Virtual SAN storage. For non-Virtual SAN sites the available RPO range is from 15 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 in the Point in time instances pane, and adjust the number of instances to keep.
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.
- Click Next.
- Choose whether you want to use replication seeds.
This option searches the selected target datastore for replication seeds. If candidate files are found, confirm whether to use the files as seeds.
- 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.
If a replication source virtual machine is powered off, the replication remains in Not Active state until you power on the virtual machine.