The virtual storage infrastructure uses a client-server model to enable logical domains to access block-level storage that is not directly assigned to them. The model uses the following components:
Virtual disk client (vdc) that exports a block device interface
Virtual disk service (vds) that processes disk requests on behalf of the virtual disk client and submits them to the backend storage that resides on the service domain
Although the virtual disks appear as regular disks on the client domain, most disk operations are forwarded to the virtual disk service and processed on the service domain.