Migration Cutover with Legacy Links
An enterprise is consolidating two legacy DAMs into a single Acquia/Widen instance. They will migrate 320,000 assets from the old systems. An inventory finds that 22% of legacy assets are referenced by live public URLs embedded in email templates, PDFs, and a public help site. The legacy vendors will shut off their systems 30 days after cutover. Internal users need a redirect or replacement path, and the help site cannot show broken images. The migration team wants to import everything in one weekend and "fix links later."
1. Why is "import everything and fix links later" a high-risk plan here, and what must be resolved before cutover?
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Why it is risky: 22% of 320,000 ≈ 70,000 assets have live external references. The legacy systems die 30 days after cutover. If the import lands assets at new URLs, every one of those references breaks the moment the old vendor shuts off - and "later" may be after the shutdown, with no source to redirect from. Email templates and PDFs are especially bad because they are already distributed and cannot be edited; a broken image there is permanent. The help site is customer-facing and cannot show broken images at all.
Must resolve before cutover:
- URL mapping: for every externally referenced asset, know its old URL and its new URL. This is the migration's real deliverable, not just the file transfer.
- Redirect strategy: stand up redirects from old URL patterns to new ones, or preserve the legacy URL structure where possible. Confirm the redirect layer survives the vendor shutdown (i.e., you host it, not them).
- The 70,000-asset subset is the priority, not the whole 320,000. Migrate and verify the referenced assets first; the long tail can follow.
- Help site: update its image references to the new URLs before cutover, and test.
"Fix later" is only safe for assets with no external references. For the 22%, the link mapping is the migration.
2. Design the cutover and the 30-day window so no external reference breaks. What do you monitor?
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Cutover design:
- Phase 1 (before cutover): migrate the 70,000 externally referenced assets, build the old→new URL map, and stand up redirects on infrastructure you control. Test a sample of email-template and PDF links end to end.
- Phase 2 (cutover weekend): migrate the remaining assets. Redirects are already live, so references resolve to the new system.
- Phase 3 (the 30-day window): keep redirects running, monitor for hits to old URLs, and only retire redirects after traffic to them drops to zero or the references are updated at the source.
Monitoring during the window:
- 404/error rates on the new asset URLs and on the redirect layer - a spike means a mapping gap.
- Redirect hit logs - which old URLs are still being requested, so you know what still depends on them and can chase down the owners.
- Help site image loads - synthetic checks on key pages.
- Referrer/source breakdown - distinguishes email/PDF traffic from help-site traffic so you can prioritize fixes.
Do not let the vendor shutdown be the deadline that forces redirect retirement; keep your own redirect layer alive past it if references remain.