For each new replication that you configure, an initial full synchronization operation is performed. During this operation, vCloud Availability copies the whole data from the source vApp or VM to a datastore in the target site. Use replication seeds to reduce the network traffic and the time that is required for the initial full synchronization of a replication.
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 copy the source vApp or VM to the target site by using 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.
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 vCloud 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. vCloud 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 vCloud Availability.