To determine the bandwidth that vSphere Replication requires to replicate virtual machines efficiently, you calculate the average data change rate within an RPO period divided by the link speed.
If you have groups of virtual machines that have different RPO periods, you can determine the replication time for each group of virtual machines. For example, you might have four groups with RPO of 15 minutes, one hour, four hours, and 24 hours. Factor in all the different RPOs in the environment, the subset of virtual machines in your environment that is replicated, the change rate of the data within that subset, the amount of data changes within each configured RPO, and the link speeds in your network.
Examine how data change rate, traffic rates, and the link speed meet the RPO. Then look at the aggregate of each group.
- Identify the average data change rate within the RPO by calculating the average change rate over a longer period then dividing it by the RPO.
- Calculate how much traffic this data change rate generates in each RPO period.
- Measure the traffic against your link speed.
For example, a data change rate of 100GB requires approximately 200 hours to replicate on a T1 network, 30 hours to replicate on a 10Mbps network, 3 hours on a 100Mbps network.