Phase 2 – Design End State
If we are not careful, data centre moves are seen as just another big IT cost, and a pretty open ended cost at that. Anyone with experience in this space knows that many moves go off the rails and that the planned dates, costs and benefits are not met. Often this is caused by trying to do the right thing and plan the migration properly but without clearly understanding the huge complexity of doing this and having the correct tools and methodology to be successful.
Given the right tools and methodologies, the design phase is where real benefits can be realized:
- Reduction in Server Hardware
- Reduction in Storage Hardware and connectivity
- Reduction in quantity of licensed software
- Reduction in Data Centre Capacity, power and cooling load
- Reduction in Maintenance Costs (hardware and software)
- Reduction in Energy use and Carbon emissions
By analyzing each of these opportunities for consolidation it becomes quite straightforward to design the ideal end state, the hardware configuration that best meets the application workload that we plan to migrate.
One possible approach is to plan for everything in the new site to be new equipment, but we rarely have the opportunity to be that simple, in general we must use a combination of new and reused computer equipment. This is done after the end state design is complete by mapping some of the underlying hardware from the old sites to the new sites. This is done in practice by either physically moving the hardware or assigning hardware that is drained of applications to the food chain for reuse. Sometimes we execute a swing move where we logically migrate applications to a temporary home, physically move the original hardware into it’s new location and then logically migrate the applications back again.
Perhaps at this stage it is useful to understand the different types of move that can be done in a data centre migration:
- Physical Move
- Logical Move
- Physical to Virtual
- Consolidation
- Decommission
- Swing Move
- New Install
- Ad-Hoc
Physical Move – uplifting the hardware, operating system and applications and moving it physically to another location. May involve physical move of storage subsystems. Involves repatching network, changes of IP address and DNS changes. May involve application changes, but unlikely.
Logical Move – Leaving the old hardware in situ, but migrating an image of the operating system and application to another piece of hardware, typically in another location. May involve upgrading the operating system and supporting infrastructure software but this is unusual due to increased risk. Involves changes of IP address, DNS changes and migration of data to new storage. More likely to require application changes than a physical move.
Physical to Virtual – A special and simple type of Logical Move supported by VMWare that can be automated. Does not support changes to operating system or supporting infrastructure software.
Consolidation – A move of the application only to a new operating system (may just be version) on a new piece of hardware. Typically new infrastructure software is installed. Data is always migrated. Requires IP address changes and DNS changes. Typically requires some application changes. Typically multiple applications are consolidated onto a single operating system image.
Decommission – Application is decommissioned. An example may be DNS servers at the end of a data centre move that are no longer required. All appliations on a piece of hardware must be decommissioned before the hardware can be decommissioned.
Swing Move – A logical move followed by a physical move of the underlying hardware and finished off by another logical move onto the moved hardware. Requires temporary equipment to support this activity.
New Install – All moves require some new hardware to be installed,
Ad-Hoc – Cannot be dealt with in a simple way like the other moves above and requires a special manual plan.
