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GeraldRamich edited this page Aug 6, 2019 · 2 revisions

Instructions for the On-Premise DG to Exchange Online migrations

Purpose: This document is to walk through migrating Mail enabled USG and UDG to O365 DL. This is down in 4 stages; this allows rollback if required. Dynamic Groups are not supported.

Stage 1 – Dump limited required Mail enabled USG/UDG setting to allow creation of “place holder” Distribution lists

Stage 2 – Create DL in O365 with properties collected. This is used to compare before and after migrations. Th DL in O365 is Hidden from the GAL and has an “Cloud” name appended to the name and properties so duplicates are not created.

Stage 3 – has two options. Option A: Remove the on premise Main enabled USG/UDG Option B: Move the on premise Main enabled USG/UDG to a non-synced OU

Stage 4 – Rename the “Cloud” DL in O365 back to original name that were created and unhide them from GAL. Note: Replication of the UDG and USG from Cloud must be completed.

Note: Error Logs are created, see Errorlogs.log

Caveats:

  • Only Mail Enabled Groups are migrated.
  • Dynamic Groups are not migrated.
  • Universal Security Groups (USG) are migrated to O365 Distribution Lists. They are NOT security enabled. Security context is not migrated.
  • If Mail enabled Groups are not deleted but moved to an OU that is NOT synced. Group Membership is not synced between on premise and cloud. Manu process is needed.
  • On-premise mailboxes will NOT see cloud only Objects until migrated to O365 mailbox. These groups will be cloud only objects.
  • Member type of the groups have only been tested with Mailboxes, not Contact or other external recipient types. They may require manual massage of data if they are not replicated or have an external target address.

Package contains 5 Scripts:

  • Step1-DumpDLsProperties.ps1
  • Step2-Create Temp Groups with New name.ps1
  • Step3-alt-Move to non-synced OU.ps1
  • Step3-Delete migrated groups.ps1
  • Step4-Rename-unhide.ps1

The Code for the scripts were found on Web and Modified to suit Customer purposes.

Requirements:

  • Exchange Organization Management
    • On premise Exchange PowerShell
  • Exchange Online Tenant Admin
    • Exchange Online PowerShell
  • Local AD Domain Admin
    • Windows AD PowerShell
  • Excel
    • Edit CSV files.

Recommend Testing in LAB environment.

  • Test USG, UDG
  • Test with nested Groups
  • Test with groups that have mailboxes and other recipient types.
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