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. See Calculate Bandwidth for vSphere Replication for details.

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.

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.