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Migrate Home Drives to OneDrive for Business

One of the wins for Office 365 customers who have OneDrive for Business included in their licensing is to migrate users' personal files to OneDrive.

For files that are stored in home drives on traditional file servers, the reduction in server and storage costs is a benefit. For other personal files stored on local computers, moving the files to OneDrive so that they are safely stored in the cloud is also a benefit.

Generally speaking, OneDrive for Business works well for:

  • “My documents” scenarios
  • Simple sharing of documents between small groups of collaborators
  • Storing data in the cloud where compliance and security can be enforced
  • Syncing files to mobile computers and devices for working offline or remotely

The OneDrive sync client can also synchronize files from SharePoint libraries for offline access to team files. So having it configure and ready to go is useful to end users who travel or work in places with poor connectivity.

In this article I'm going to demonstrate a simple migration scenario for migrating home drives to OneDrive for Business. For the purposes of this demonstration the environment consists of:

  • Office 365 E3 licensed users.
  • Office 2016 (via Office 365 ProPlus) client installations on Windows 10 computers.
  • The “Next Gen Sync Client” (NGSC), also generally referred to as OneDrive.exe, as opposed to the old Groove.exe sync client that has different features, performance, and reliability.
  • User home drives located on a file server
  • Folder redirection for Documents and other well known folders to the home drives

Reviewing Home Drive Data

OneDrive for Business has some limitations for synchronizing files, which includes things like:

  • Invalid characters in file names (e.g. #, %, ?)
  • Specific strings of characters in file names (e.g. COM1)
  • Specific strings in folder names
  • Maximum of 30 million documents per library
  • 10GB file size limit
  • Files names or paths with more than 256 characters

Those limitations may change over time, so you should always review the latest information on Microsoft's support site. There's a variety of other limits and user experience caveats to be aware of as well.

But for the file limitations, an analysis of the data your planning to migrate would be advisable. This could be as simple as a PowerShell script that recursively scans the file server to look for the issues above. If you qualify for FastTrack support from Microsoft, that service includes analysis and remediation as part of the process (and you can use them for the entire migration, so you don't need to read this article at all if you don't want to).

Reviewing OneDrive for Business Admin Settings

The OneDrive for Business Admin portal allows you to control a variety of settings for OneDrive users, such as whether they are able to share content external to the organization, sync with non-domain joined computers, how files can be used from mobile devices, DLP policies, and more. Before you proceed with your OneDrive migration, it's worth reviewing the settings to make sure they align with your expectations and security policies.

For example, you might consider it necessary to disable sharing of SharePoint and OneDrive content with external users, or limit syncing of files to domain-joined computers only.

Configuring a Group Policy

OneDrive has a Group Policy template available from Microsoft. The OneDrive GPO can be used to set the default location for the OneDrive folder, among other useful settings. That particular setting, in combination with a standard folder redirection policy, is how I'll be handling the migration in this environment.

The objective of the Group Policy is to:

  • Create an environment variable representing the OneDrive sync location, so that the variable can be used in the Group Policy folder redirection settings. I've used Microsoft's guidance here. The variable in this example is set to “%userprofile%\OneDrive – Exchange Server Pro”.
  • Create a new folder in the %OneDriveSync% location. This can be achieved with a Group Policy preference.
  • Preventing users from choosing a different OneDrive location on the user's computer. Note that this requires editing the Group Policy template (ADMX file) in the Central Store with your tenant ID. This ensures that the default path of “%userprofile\OneDrive – Tenant Name” is used. Although the GPO template can also be edited to specify a different sync folder, it doesn't seem to work with variables at all. In my experience it's easiest to just accept the default path and then restrict users from changing it. Edit: this article now explains to use a REG_EXPAND_SZ instead of REG_SZ so that variables work.
  • Apply a new folder redirection policy that directs Documents and other folders to the %OneDriveSync% location instead of the home drive on the file server (the policy will move existing files as well).

For this environment I've placed the OneDrive GPO as a higher priority than the existing folder redirection GPO. I've also scoped the OneDrive GPO only to members of the “OneDrive for Business Users” security group, and denied the “Apply” permission for the previous folder redirection GPO for the “OneDrive for Business Users” group. Note that after removing Authenticated Users from the scope of the new policy, you then need to go to the Delegation tab and delegate the “Read” permission for the GPO, or you may find it does not process at all.

So in effect this all means I can roll out OneDrive to users by adding them to that security group. There is also some end user communication involved in the whole process. You'll want to make sure your users are expecting the change so there's no surprises or confusion.

Something to be aware of is that the folder redirection will overwrite any existing data in the destination location that has the same file name and path. If any of your users have already begun using OneDrive and storing files, you should manually deal with those to avoid conflicts. You can find active OneDrive users in the usage reports in the Office 365 admin portal.

Configuring the OneDrive for Business Sync Client

After the GPO has applied, when the user signs in to OneDrive, it will begin syncing that existing data in the local path to the cloud. For environments without any SCCM or other systems in place to initiate a program running in the context of the user, a workaround is to email the user a link to odopen://, which will trigger the OneDrive client to launch. Since you likely want to send them some login instructions and other general adoption advice for OneDrive, you can simply bundle all that up into a single email.

When the user opens OneDrive they'll be able to walk through the setup process. You should ensure that the instructions you provide are clear about what they should do at each step of the initial configuration wizard.

Monitoring the Deployment

The initial synchronization of files to OneDrive may have a detrimental impact on your network performance. Monitor your network utilization so that you don't roll out too many users simultaneously.

You can continue to use the OneDrive usage reports in the Office 365 admin portal to track the adoption of OneDrive by your users.

It's also possible to quickly pull a report of OneDrive usage by using PowerShell.

Completing the Migration

Once you're satisfied that user home drives have been migrated to OneDrive for Business, you can do a scan of your file server to confirm that the home drives for users are empty, and then start decommissioning those shares so that the storage can be reclaimed. For any users who have not logged on and completed their migration you can manually assist them, or back up their home drive files elsewhere, or even upload the files to their OneDrive in the cloud yourself so that they're waiting for initial sync to the client.

Paul is a Microsoft MVP for Office Servers and Services. He works as a consultant, writer, and trainer specializing in Office 365 and Exchange Server. Paul is a co-author of Office 365 for IT Pros and several other books, and is also a Pluralsight author.
Category: OneDrive



    One thing we have noticed preservation policy will occupy the storage space of one drive so if we enable preservation policy for the e-discovery then the users will have less quota then actual number

    more over it has view limit and version enabled for all the documents. until this issue resolved one drive cannot replace network drive.

  2. JK says:

    Im working on this for 180k users globally. There are few other points to mention as well. Folder redirection is interesting option to pre-populate ODB cache and save on initial synchronization. Which of course depends on average size og Home drives but they are usualy are not small.

    For completnes I would like to mention the O365 Adoptation Dashboard on powerBI which is great tool for post migration activities like gamification and management reporting https://blogs.office.com/2016/10/10/announcing-the-preview-of-the-office-365-adoption-content-pack-in-power-bi/

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