Intra-Forest Migration and Office 365 - Notes from the Field - Part 1

Introduction
The purpose of this series of blogs is to share a "real-life" migration experience in which a multitude of technologies were used to provide the required solution and the toolsets used to allow us to make that journey. In Part 1 we will look at where we started and where we need to get to. During the series will look into greater detail at each key stage which will discuss Pit falls, quick wins and "known issues"

 Problem Statement
Customer A has a large number of Subsidiary  Businesses compromising several thousand of employees. With a highly de-centralised IT operations model with each business being autonomous for its own domain. The IT Estate was also aging with little or no support. There was also a large amount of unmanaged Messaging data in the form of PST files because of highly restrictive storage limitations.

Business Requirements
The desired end state was to create a much more Simple and Manageable IT solution with each Business still requiring a degree of  autonomous administration. The solution must also provide enhanced collaboration and communications.

Current Environment
The current topology was a Single Active Directory forest (Windows 2003) compromising a number of Child domains with an Exchange Organisation across the forest and each domain. (Exchange 2003)

Design Goals and Decisions

Design Goal - A more Simple and Consolidated Directory Platform
Design Decision - was to migrate all users, Computers, Servers, Groups to the root domain and collapse each child domain.
Dell (Formerly Quest) Migration Manager for Active Directory was the chosen tool. Part 2 will discuss important preparation tasks and considerations that are needed before we start an Intra-Forest Migration.

Design Goal - Autonomous Admin
Design Decision - Each Business Unit has its own Organisational Unit with delegated administration with only the required rights.

Design Goal - Replace the Aging, Unstable and Limited Exchange 2003 Platform
Design Decision - Office 365 was chosen to provide the Communication, Collaboration and Messaging Platform (Exchange, Lync, SharePoint & Yammer) . MobileIron Cloud provided continuous support from the legacy environment to Office 365. Check out Part 2 on how we planned and executed the co-existence and migration to Office 365.

Design Goal - Manage Legacy Archive and all future messaging data.
Design Decision - Symantec EV.Cloud was chosen to provide all mail arching and legacy pst management.

Design Goal - Keeping it Simple. Users must only require a Single User Name and Password to access all platforms.
Design Decision - ADFS and Dirsync was implemented to provide SSO (Single Sign On) for Office 365 and Symantec EV.Cloud **(Check out later posts for some "Known" limitations/features of SSO.

Design Goal - No Single Points of Failure
Design Decision - Office 365 and Symantec by design offers this technology by default. To match the resilience within the on-promised ADFS Design. The solution was dispersed across multiple datacentres and servers. We will cover this in more detail later in the series.
 
So we have our challenge, Some key design decisions. In part 2 we will look start to look at each stage and Identify how we get there and highlight some important processes and considerations that need to be understood.