A Cloud Extension is a conduit for VM storage between two hosting environments, such as:
- An on-premises data center and Google Cloud
- AWS and Google Cloud
A Cloud Extension uses a dual-node active/passive configuration for high availability; each node serves its own workloads while providing backup for the other.
Cloud Extension deployments on Google Cloud
A Cloud Extension is a pair of Cloud Edge nodes,
known as Node A and Node B.
Determining the number of Cloud Extensions you need
Each Cloud Extension supports 10–50 concurrent VMs. You can run more than one Cloud Extension simultaneously to handle a larger migration.
The total number of Cloud Extensions necessary for a migration is a function of the total number of VMs divided by the capacity of the Cloud Extension. For example, for a migration of 1000 VMs, Velostrata recommends using five Cloud Extensions, each hosting 50 VMs. The migration would use these Cloud Extensions in four waves.
Cloud Extensions are created and configured either using the Velostrata vCenter plug-in or the Velostrata Manager.
Cloud Extension sizes
The available Cloud Extension VM sizes are:
| Relative size | Number of VMs | Instance type | Cache disk storage | Temporary disk storage | Core disk storage |
| Small | 10–15 | n1-highmem-2 | 250 GB | 100 GB | 20 GB |
| Large | 16–50 | n1-standard-8 | 1024 GB | 250 GB | 100 GB |
Impaired Cloud Extensions
A Cloud Extension is impaired when it has not fully failed, but is experiencing trouble with one of its nodes or network connectivity. For more information, see Cloud Extensions high availability model.
What's next?
- Learn more about Setting up a Cloud Extension.
- Learn more about Stopping and starting a Cloud Extension.
- Learn more about Repairing a Cloud Extension.