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Data Migration Strategies for Self-Hosted Apps

Moving from SaaS to self-hosted means migrating your data. Here are battle-tested strategies for zero-downtime data migration.

migrationdatadevops

The Migration Challenge


You've decided to switch from Notion to Outline, or Slack to Mattermost. Your data needs to come with you.


Step 1: Export


Every SaaS provides data export (GDPR requires it). Common formats:

  • JSON: Structured data, easy to parse
  • CSV: Tabular data, universal
  • SQL dump: Database-to-database migration
  • ZIP with files: Documents, images, attachments

    • Export Quality Varies

    Some exports are complete (all data, all metadata). Others are minimal (just content, no timestamps, no relationships).


    Always export and inspect BEFORE starting the migration project.


    Step 2: Transform


    The export format rarely matches the import format exactly. Common transformations:


    Field Mapping

    Source: { "userName": "Alice" }

    Target: { "display_name": "Alice" }


    Date Formats

    Source: "01/15/2024" (US format)

    Target: "2024-01-15T00:00:00Z" (ISO 8601)


    Rich Text

    Source: Notion blocks format

    Target: Markdown


    Relationships

    Users, tags, categories often use different ID systems. Build mapping tables.


    Step 3: Load


    Batch Import

    Insert all data at once. Simplest approach.

  • Best for: One-time migration, small datasets
  • Risk: If it fails midway, you might have partial data

    • Incremental Import

    Import in batches with checkpoints. Resume-safe.

  • Best for: Large datasets, unreliable network
  • Approach: Track last imported ID, continue from there

    • Dual-Write

    Write to both old and new systems simultaneously. Verify parity, then switch.

  • Best for: Zero-downtime migration of critical systems
  • Most complex but safest

    • Common Migration Paths


    Slack → Mattermost

    Mattermost has a built-in Slack import tool. Export from Slack, import to Mattermost.


    Notion → Outline

    Export from Notion as Markdown. Import to Outline.


    Google Workspace → Nextcloud

    Export via Google Takeout. Import files to Nextcloud, contacts/calendar via CardDAV/CalDAV.


    Trello → Plane

    Export from Trello as JSON. Use Plane's import feature.


    Migration Checklist


    1. Export all data from source (verify completeness)

    2. Set up the new tool on TinyPod

    3. Write transformation scripts if needed

    4. Import to a test instance first

    5. Verify data integrity (counts, spot checks)

    6. Import to production

    7. Verify again

    8. Run both systems in parallel for 1-2 weeks

    9. Switch DNS/links to new system

    10. Decommission old system after grace period