forked from docs/blueprints
129 lines
4.6 KiB
ReStructuredText
129 lines
4.6 KiB
ReStructuredText
Application Migration
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---------------------
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Based on T-Systems' successful practices and experience in serving a large
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number of customers, Open Telekom Cloud had identified four main phases in the
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migration process. An understanding of these four phases makes it easier
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to ensure a smooth migration.
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.. image:: ../../assets/caf/image42.png
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Phase 1: Application analysis
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******************************
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The services and functions provided
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need to be clearly identified, along with the technology stacks,
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deployment modes, SLAs, and dependencies. You need to know where the
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applications come from and how the O&M is handled.
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The research includes, but is not limited to:
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- Application architectures
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- Application modules, internal and external dependencies, and the
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languages and frameworks used
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- Application hosts, including host configurations, specifications,
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operating systems, total data volume, NICs, HA deployment, as well as
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DR and backup requirements
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- Databases, including the types and versions, how much data needs to
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be handled, and the performance and HA requirements
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- Middleware, including the types (such as message middleware and cache
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database), versions, as well as cluster scale and capacity
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Phase 2: Migration planning
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***************************
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Based on the information collected in
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Phase 1, assess applications using the **6R model** (Rehost, Replatform,
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Refactor/Rearchitect, Repurchase, Retire, and Retain) and following
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the general principles described here. Analyze application readiness
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and benefits and identify proper migration paths.
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- General principles for migrating applications to the cloud
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- For third-party SaaS services, as long as they can keep up with
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service development, keep them unchanged.
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- For purchased software deployed on hosts, rehost or replatform them
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to migrate them to the cloud.
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- For applications that are not ready for cloud, for example,
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applications with incompatible host OSs, applications with
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outdated, unavailable, or unsupported components, or applications
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whose benefits from migration seem elusive, keep these
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applications on premises.
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- For self-developed applications, rehost, replatform, or rearchitect
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them, depending on the technical stack requirements of customers.
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- For components such as databases and middleware, if there are
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available cloud services, replatform them, use pay-per-use billing
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for the best cost-effectiveness, and so you don't have to worry
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about the O&M.
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- Principles for prioritizing applications for migration
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Prioritize applications to be migrated based on the expected benefits
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and on their readiness. Migrate applications in the order shown in the
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following figure. Start with those that are easy to migrate and can
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benefit much from migration, and give low priority to applications that
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are more difficult or that will benefit little.
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.. image:: ../../assets/caf/image43.png
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Business Benefits Considerations
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Considerations for business benefits include but not limited to:
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- Improving performance, increasing efficiency, and reducing costs
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- Changing service requirements
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- Enhancing user experience
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- Serious architecture issues
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- Auto scaling requirements
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- Compliance
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Cloud Readiness Considerations
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Considerations for cloud readiness include but are not limited to:
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- Service complexity
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- Maturity of business and IT design
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- Dependency
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- Organizations and capabilities
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Phase 3: Migration planning of pilot applications
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*************************************************
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Select pilot
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applications based on the overall migration path planned for your
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applications, plan the migration of the pilot applications, and
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estimate the costs involved. Proper planning streamlines the
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architecture and helps ensure a successful experience, which, in
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turn, supports future migrations.
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Phase 4: Implementation and summary
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***********************************
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After developing the migration
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plan and getting budget approved, migrate the pilot applications to
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identify what the company should focus on in terms of technology,
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organization, process, talent, and cost. This phase is critical to
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accumulating practical experience. This phase helps companies more
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confidently migrate applications to the cloud and benefit more from
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the migration.
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When using the 6R methodology, the migration paths are as follows:
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.. image:: ../../assets/caf/image44.png
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The following section covers the Rehost, Replatform, and Rearchitect
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migration paths.
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.. toctree::
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:maxdepth: 1
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rehost.rst
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replatform.rst
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rearchitect.rst
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migration.rst |