For each new replication, VMware Cloud Director Availability performs a full initial synchronization copying the entire source data from the vApp or VM to a datastore in the target site. Use a replication seed to reduce the network traffic and the required time for the replication initial synchronization.
Due to the size of the vApp or VM or to the network bandwidth, an initial full synchronization might take a long time. To reduce the initial synchronization time, you transfer the source vApp or VM to the target site. Use removable media, failover of a previous replication, or other means of data transfer. Then, in the target site, configure a replication that uses the vApp or VM copy as a replication seed.
Use a VM as a Replication Seed
To use a VM as a seed, in the target site, select a VM that has an identical disk configuration with the seed VM. The size and number of disks, and their assignment to disk controllers and bus nodes must match the replication source and the seed VM.
For example, if a replication source VM has two 4 GB disks, one of them assigned to SCSI controller 0 at bus number 0, the second one to SCSI controller 1 at bus number 2. Your seed VM must have the same hardware configuration - two 4 GB disks, at SCSI 0:0 and at SCSI 1:2.
The disks in the source virtual machine must match the disks in the seed VM. Else the reverse replication fails with a Disks of provided seed VM don't match the disks of the source VM message. For more information, see Selecting Replicated Disks.
Use a vApp as a Replication Seed
To use a vApp as a seed, in the target site, select a vApp that has an identical VM set with the seed vApp. The VMs in the seed vApp must have a matching name to the VMs in the source site vApp. Each VM in the seed vApp, must meet the prerequisites to be a seed VM of the VM with the same name in the source site.
After you start a replication, in the VMware Cloud Director™ inventory, the seed vApp is empty and you can manually copy the vApp settings and metadata that are not replicated from the source site. The seed vApp remains available as an empty copy and you can remove it at your discretion.
Create a Replication Seed
Use one of the following methods to create a seed vApp or VM in the target site.
- Offline data transfer: Export the VM as an OVF package and a Cloud service administrator imports the package to your cloud organization.
- Clone a VM: Create a seed vApp or VM by cloning the vApp or VM from the target site. VMware Cloud Director Availability calculates the checksum and exchanges the different blocks from the replication source to the seed vApp or VM.
- Failover data from a previous replication: Set up a replication, fail over to the target site and continue using the on-premises workload. At a later point, you protect it in the target site by using the VM that you failed over earlier as a seed.
- Copy over the network: Copy a source VM to the cloud organization and transfer the source data to the target site by using other means than VMware Cloud Director Availability.