The client's request was to partly migrate on-premise infrastructure to the cloud.
As per the customer’s requirements, the application services should have been hosted in the cloud for cost reduction and efficient scaling. The database cluster should have been replicated in the cloud to cut costs of disaster recovery infrastructure and reduce downtime, but the write nodes should have remained in the local data center.
In detail, the project scope included three key deliverables:
- to migrate 4 large Microsoft Hyper-V application services to AWS for automatic scale in/out;
- to replicate 4-node Microsoft SQL Server DB cluster to AWS (while the nodes must have remained in the client's datacenter);
- to migrate 2-node DWH and Reporting Service machine to AWS.
During the implementation, the team had to tackle certain challenges associated with:
- diverse infrastructure, complex security rules, thousands of clients over LAN;
- legacy application (Borland C++). Due to that, there was the possibility of instance failures, as well as no automatic disaster recovery;
- complex database with intense usage of triggers, transactions, and stored procedures;
regular spikes in the workload.