Harsha,
From a Delphix virtualization engine in the cloud, you can link to a source database on-premises to create a dSource. Whether you have the network bandwidth and permissions to do so is up to you.
The reasons for instead linking to a Delphix virtualization engine on-premises and then replicating to a Delphix virtualization engine in the cloud are...
- data volume: linked dSources are usually about 1/3rd the size of their source databases, so replicating already-linked dSource(s) from an on-premise Delphix engine to a Delphix engine in the cloud means less data to transfer across what might be a limited network link
- security: your company's security requirements may prevent confidential data or personally-identifiable data from leaving on-premises, so having a Delphix engine on-premises allows you to mask or obfuscate data first, then replicate only the masked data to the Delphix engine in the cloud. Corporate security might also prevent anything in the cloud from accessing production systems as well, so a local on-premise Delphix virtualization might also be a requirement from that perspective
- OS platform for Oracle: If the source database is on Oracle on a "legacy" UNIX platform such as Solaris, AIX, or HP-UX, then it likely will need to be converted cross-platform to Linux before it can run on the Linux x86 servers in the cloud. That cross-platform provisioning from legacy UNIX to open-source Linux can be performed at a Delphix virtualization engine on-premises first, and then replicated to a Delphix engine in the cloud where only Linux database servers are available
If you do not have these requirements, then you probably don't need a Delphix virtualization engine on-premises to complement the one in the cloud.
Please let me know if this makes sense?
Thanks!