First thing’s first, what do we actually mean by website migration? In its simplest form, migration is the process of moving from the use of one operating environment to another operating environment that is, in most cases, thought to be a better one. Migration can involve upgrading to new hardware, new software or both.

At BT48 our migrations have most recently involved transferring data from one Content Management System (CMS) to another — either an older version of Drupal to Drupal 8 or from another CMS like WordPress, Expression Engine, or Terminal4 to Drupal 8.


A site migration and redesign is not a one-step process and obviously there are some risks involved with the process. However, over the years we at have gained a great deal of experience and expertise around migration and have developed a process to mitigate these risks involving 3 separate stages:

  1. Pre-migration
  2. Launch
  3. Post-migration.


1. Pre-Migration

  • Scope
    The initial phase involves finding out from you as the client what data needs to be migrated and what data needs to be transformed as part of the migration.
  • Requirements Gathering
    Once we scope the extent of the project we gather our requirements and ensure that all stakeholders are aware of the implications of leaving data behind.
  • Mapping
    We custom views on the origin database to reduce calls for related data. For Drupal migrations we usually utilise a custom mysql connector along with custom migration modules and drush commands that allow the export and import to be completed alongside each other. In addition, our custom migration module allows us to change connection details and export locations on the fly.
  • Planning
    We work with clients to ensure that data can be added to the system during the migration and that the test site can continue to use the latest data. Migration is carried out on a daily basis and only new and changed records are exported/imported.

2. Launch

  • Test Migration
    Our hosting partners at Pantheon provide us with as many test environments as required with quick launch and independence from each other. We usually setup a test site for for initial data inspection and exports though after export/mapping criteria is finalised exports are able to be completed from the live environment. The Drupal 8 migration process means that if functional changes require the migration to be run in its entirety, or across certain entities, then the fine grained nature of the tools allow for this.
  • Migration
    Migration is usually executed in a number of stages:
  1. Close all update functionality to current live site.
  2. Run export commands against current live site.
  3. Import data into new live environment.

3. Post-Migration

  • Validation
    Post migration validation consists of matching entity counts on both new and old systems and visual inspection of select records that covers a wide spectrum of imported data.


At we understand that the above process always needs to be tailored to suit your business/organisation’s unique migration needs.

We believe that from the outset, in any migration process, clear, honest and open dialogue between you as the client and the web development agency is essential. This ensures that your the website created is one that best suits your clients’ needs, matches your business objectives and that the migration process flows as smoothly as possible.


For further information on website migration support, please don’t hesitate to contact us at