The end state architecture is derived in order to formulate a migration strategy that considers a wide range of constraints, interdependencies, business impact, resource impact, and cost impact. It needs to incorporated thorough risk analysis against all plans and recommendations reviewed with all relevant stakeholders and decision makers.
The target cloud design consider the below:
- Application architecture landscape.
- Cloud infrastructure architecture comprising of virtual server, storage and network.
- Disaster recovery, monitoring and management architecture.
At this point, it will take into factor the strategy for migration, application dependencies and requirements to devise a cloud migration design which can be successfully implemented with minimal impact to the business. It will also ascertain the cloud migration methodology as to whether the cloud migration will be done in a phased manner or it will any other approach e.g. agile, big bang, etc. Accordingly it will devise an execution plan, prepare test checklists and end state architecture diagram consisting of the low level design (LLD) and build approach.
The inputs consists of the migration strategy, the application dependencies and the defined and agreed requirements. It will provide the defined cloud target architecture for the technology areas impacted. In the cloud migration project, the following technology areas are considered within infrastructure;
- Network (Local Area Network (LAN) and Wide Area network (WAN))
- Perimeter security
- Infrastructure application impact for;
For each technology area, an approach, for co-existent and future mode of operation will be defined with a deep understanding of technology and designing. Develop a detailed execution plan for implementation of the target infrastructure, and defined bundles of migration.
The application LLD will define an application infrastructure, into various categories such as decommission, virtualization, and lift-and-shift. It will define any tools which will be required for migration, e.g. Racemi, AWS VM Import/Export, AppZero, ATADATA, and/or VMware converter for virtualization, which then will be sent for procurement.
- Develop migration approach.
- Decide which of the services and applications will remain within the cloud and which would remain behind the firewall or on the private cloud.
- Provide overview co-existence of the application architecture.
- Design the low-level application end state.
- Design the low-level cloud infrastructure end state.
- Develop the operations plans e.g. standard operating procedures (SOP), handover to support checklist, etc.
- Develop the execution plan.
- Address the applications architecture that is not appropriate with the cloud.
Hints and tips
- It is important to achieve high reliability, low cost, and good maintain-ability.
- The LLD is the order of an application that connects individual components.
- The goal a low-level design document is to give the internal logical design of the future state application architecture.
- Structure the design and start with the table of contents with the most important chapters of the document.
- Capture the decisions, a design document is all about decisions to meet the requirements.
- Keep it short, quantity does not automatically make a good document.
- A picture is worth a thousand word, pictures or diagrams are an excellent tool for visualizing an application architecture LLD.
- The LLD is based on the high level design (HLD) document.
- A good LLD document makes the application architecture easy to implement.