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Feedback – Migrating TFS to Azure DevOps

01 February 2022

By Lionel Gurret.


Sokube teams recently had the opportunity to migrate an on-premise TFS Server infrastructure to Azure DevOps Services cloud offering.

There are many reasons why you might want to do this:

  • Getting automatic updates from Microsoft
  • Optimizing financial costs and reducing operational time
  • Complying to certifications (ISO 27001, SOC 1, SOC 2 and HIPAA BAA)
  • Accessing the platform from to Azure DevOps from anywhere and on any device
  • Getting a 99.9% uptime guarantee
  • Support

In this article, we will detail the different steps necessary for the migration process and then we will share our feedback and the difficulties encountered.

Intervention procedure

The following workflow illustrates the different stages of the migration process that we will analyze:

0 – Azure DevOps Server (TFS) Update

Before you can start the migration, it is necessary to have a recent version of Windows (Windows 2019) and a recent version of Azure DevOps Server (2020).

    No difficulty encountered. It is important to provide enough hardware resources (disk, CPU, RAM) for the operation.

1- Firewall modification

The first step of our migration consists in cutting the firewall (port 80 and 443) on the production (local and/or external firewall) in order to avoid modifications on the different TFS collections.

2 – Cleaning the collections databases

This step is the most important. Indeed, significantly reducing the size of your collections will allow you to migrate more easily and quickly to Azure DevOps Services.

All the necessary commands to optimize the size of your collections are nicely detailed in the following article : How to reduce the size of your TFS/Azure DevOps Server collection databases

    Data volumes should not exceed 30GB per collection. If this is not the case, it is advisable to go through an intermediate Azure server to perform the migration. Using these queries we were able to reduce the size of collections from 110GB to 20GB!

3 – Validation of the data to be migrated

We can now operate the actual data transfer. The first step before uploading a dataset into Azure DevOps is to validate it on Azure DevOps Server 2020.

  • Download TFS Migrator
  • Run the following system command on your collection(s):
    Migrator validate /collection:{Collection URL} /tenantDomainName:{Name}

    The migrator should ask you to configure, configure the time zone that corresponds to the time zone of your Azure Tenant. (ex: WEU) In order to be able to continue the migration process, please resolve all the errors reported by the migrator. Here is some helpful [documentation ](https://aka.ms/AzureDevOpsImportTroubleshooting)for the various known errors. On our side, we only had one warning related to a “database collation” which could be ignored.

4 – Preparing for migration

This step is similar to the previous one. Here we will generate the import.json and IdentityMapLog.csv files, used by the migration tool.

  • Run the following system command on your collection(s):
    Migrator prepare /collection:{Collection URL} /tenantDomainName:{Name}

    Answer the various questions of the wizard, then validate the IdentityMapLog file. Correct on Azure Active Directory the account or accounts that would not have been synchronized. We had no problem, all accounts were well synchronized!

5 – Generating a DACPAC file

    To be able to transfer the data present in our databases, it is necessary to generate a [DACPAC ](https://docs.microsoft.com/en-us/sql/relational-databases/data-tier-applications/data-tier-applications?view=sql-server-ver15)file from the SQL Server databases. This file contains a collection of XML files that define the schema and the data to transfer. It will be used by Azure DevOps Services for migration.Steps to perform:
  • Detach your collections from Azure DevOps Server
  • For each of your collections, generate the DACPAC file(s) via the following command line:
cd "C:Program Files (x86)Microsoft Visual Studio2019CommunityCommon7IDEExtensionsMicrosoftSQLDBDAC130" 

SqlPackage.exe /sourceconnectionstring:"Data Source=localhost;Initial Catalog={COLLECTION DB NAME};Integrated Security=True" /targetFile:{DACPAC FILE PATH} /action:extract /p:ExtractAllTableData=true /p:IgnoreUserLoginMappings=true /p:IgnorePermissions=true /p:Storage=Memory

You must then copy your DACPAC to an Azure blob container storage.

This operation can be done manually via the Azure Container Explorer or more quickly using AZCopy:

    azcopy make 'https://<storage-account-name>.file.core.windows.net/<file-share-name><SAS-token>'

6 – Editing the import.json file

In step 4, an import.json file was generated in the folder C:migrationLogsCollection-NameDate.

Open the file and complete it for the dry-run migration:

Replace the following fields:

  • Location : Provide the SASKey of your Azure storage container
  • Dacpac : Enter the path of your uploaded DACPAC file
  • Target Name : The name of the Azure DevOps organization to create (use a temporary name for a dry-run)
  • ImportType : Put DryRun to do a migration test or Production for a definitive migration.
    With a dry-run migration, you ensure that the migrated data will be automatically deleted between 15 and 21 days after migration.

7 – Launching the migration

Now run the following command for each of your collections:

    Migrator import /importFile:C:migrationLogsCollectionXXXXXimport.json

A link will be provided to follow the import progress:

Once the migration has started and is complete, an email will be sent.

    We experienced high variance in durations for the same interventions and the same data volumes (from 3 to 10 hours.) These variations are largely explained by the fact that there is no control over the schedule used by Azure platform to perform the migration, this could happen during peek hours.

You can now validate the migrated data with your users before proceeding to the final intervention.

Feedback and difficulties encountered

Once the databases are reduced, the Azure DevOps migration process is very reliable.

Nevertheless, several points must be taken into account to perform succesfully such a migration:

  • Make sure you configure your AAD (Azure Active Directory) correctly. This step will allow you to have your groups and users configured directly after the migration.
  • Remember to reserve your organization name (ex: my-great-place-to-work) in Azure DevOps as soon as possible. It is possible to rename an organization at any time. So you can do your tests (dry-run) on temporary organizations (ex: my-great-place-to-work-test1).
  • Cleaning databases can be tedious. Indeed, some automatic cleaning jobs did not work on the server to be migrated. It is therefore interesting to take care of the cleaning of the databases in a first planned intervention by relying on a VM snapshot.
  • Establish a user validation plan beforehand with your developer teams (pipelines, release definitions)
  • Retrieve via the Azure DevOps API the pipelines and release definitions of your first dry-run migration using self-hosted agents. Indeed, since self-hosted agents are not migrated by Azure DevOps, your pipelines will not have agents configured.


How to reduce the size of your TFS/Azure DevOps Server collection databases

Migrating from TFS to the Cloud… Without Losing Your Mind

Azure DevOps Server to Services Migration overview – Azure DevOps

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