Manage Data -> Migrate to ILM landing page is only valid for ECE / ECH

[eedugon]

Type of issue

Other

What documentation page is affected

https://www.elastic.co/docs/manage-data/lifecycle/index-lifecycle-management/migrate-index-management

What happened?

I'd like to explain an issue with the landing page, and share some proposals:

The title of the root / landing page (Migrate to ILM) looks good. It should be a page with the objective of explaining users how to start using ILM in clusters where they were not using it (they might have been using curator or just performing manual management of their indices).

The problem is with the content of that landing page.

The current content is the migrated content of the ECH and ECE docs that described a very specific use case and need, migrating from the internal platform feature called index curation (which internally used curator but that was transparent to users) to ILM, because at some point we discontinued that component in favor of relying on ILM.

So, that document is only valid for ECH and ECE, and currently the applies_to says stack, which is incorrect.

But we cannot leave a landing page of this section with a doc and narrative that is only valid for ECE and ECH, and for a very special case, so my recommendation is:

1. The current content of the page should go to a sub-page called Migrate to index lifecycle management on ECH and ECE or Migrate from index curation to ILM on ECH and ECE, and something shorter in the TOC :).

• Ensure that the doc clearly explains its scope, which is how to migrate from the legacy functionality called index curation that only existed in ECE and ECH platforms for old deployments (probably not applicable anymore almost to anyone, more over in ECE 4.x where all deployments are expected to be on 8.x at least) to ILM. (FYI, before ILM existed, that index curation was a feature offered by ECE and ECH for users to configure automatic deletion of indices, but doesn't exist anymore).
• The applies_to should only mention ECH and ECE.

2. Rewrite the landing page as an introduction to the topic, explaining the scope of the section and with links to the other pages:

• Explain that the doc intends to guide users to migrate to ilm from a system that was not using ILM before.
• For ECE and ECH users running old deployments they might need to migrate to ILM from the legacy index-curation functionality (and we introduce a link to the doc).
• For users that were managing their data manually or with other mechanisms (such as curator)... -> LINK to Manage existing indices.
• For systems that were relying on node attributes + index allocation filters we also recommend to move to node roles + _tier_preference, as that's how ILM works by default now (+ LINK TO migrate index allocation to node roles)

The other 2 pages look good:

• The page called Manage existing indices looks good and makes sense. Valid for all deployment types, as it's informational. I wouldn't change anything there.

• The page Migrate index allocation filters to node roles also looks good, and it covers all deployment types.

Additional info

No response

cc: @kilfoyle , as you are working in this area currently.