DOC-7145: Document coordinated Active-Active database upgrade

[tedraykov]

Rewrites the Active-Active upgrade page around the coordinated upgrade in Redis Software 8.0.18 and later. You now upgrade the database with a single crdb-cli crdb upgrade or POST /v1/crdbs/{crdb_guid}/upgrade request. Also adds a crdb-cli crdb upgrade reference page and lists upgrade in the crdb-cli overview.

Jira: DOC-7145

Conflicts with #4142. This PR removes the "Update module information" section that #4142 adds its --update-db-config-modules warning to. The warning needs a new home, possibly under Upgrade limitations. Its point that crdb-cli crdb upgrade pins module versions again in the default configuration applies to the procedure documented here.

Needs verification:

• The crdb-cli crdb upgrade flag names come from the upgrade options table and haven't been checked against --help on 8.0.18 or later.
• keep_crdt_featureset_version appears in the options table but not in the REST reference for POST /v1/crdbs/{crdb_guid}/upgrade.
• The REST API accepts a modules field. It's unclear whether crdb-cli crdb upgrade has a matching flag.

🤖 Generated with Claude Code

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Note

Low Risk
Documentation-only changes to upgrade procedures and API/CLI reference; no runtime code, though operators may follow the new flow and drop older per-instance steps.

Overview
Rewrites the Active-Active database upgrade guide for Redis Software 8.0.18+ coordinated upgrades: one crdb-cli crdb upgrade or POST /v1/crdbs/{crdb_guid}/upgrade call upgrades all participating clusters instead of per-cluster rladmin steps.

The page now leads with what the coordinated upgrade does (Redis/modules, module config sync, feature set), adds default Redis version and prerequisites (cluster upgrades, version support, backups, client compatibility), and puts crdb-cli first in multitabs with --preserve-roles, optional --redis-version, task polling, and post-upgrade rladmin status checks. Status troubleshooting is reframed around coordinated behavior and keep_crdt_protocol_version / keep_crdt_featureset_version instead of separate featureset and “update module information” procedures.

Adds a new crdb-cli crdb upgrade reference (flags, returns, examples) and mentions upgrade in the crdb-cli overview. Documents keep_crdt_featureset_version on the REST upgrade request body.

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[CLAassistant]

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[github-actions]

DOC-7145

[github-actions]

🧠 Redis Memory

Found 7 related items from repository history (2 new this commit):

• PR — RS: Added module commands limitation during A-A DB upgrades to Redis 8.0 to additional docs

• PR — RS: Clarified that upgrading existing Active-Active DBs to Redis 8 will not automatically enable any modules

• PR — RS: update-db-config-modules warning

• PR — RS: document redis_version in CRDB database_config object

• PR — RC: Remove A/A upgrades and add 8.6

• Commit — DOC-7145: Document coordinated Active-Active database upgrade 🆕

  DOC-7145: Document coordinated Active-Active database upgrade

• PR — RS: Added note that upgrading existing Active-Active DBs to Redis 8 will not automatically enable JSON 🆕

  Staged previews:

Memory updated at 16b713e

[github-actions]

Staging links:
https://redis.io/docs/staging/DOC-7145/operate/rs/installing-upgrading/upgrading/upgrade-active-active/
https://redis.io/docs/staging/DOC-7145/operate/rs/references/cli-utilities/crdb-cli/
https://redis.io/docs/staging/DOC-7145/operate/rs/references/cli-utilities/crdb-cli/crdb/upgrade/
https://redis.io/docs/staging/DOC-7145/operate/rs/references/rest-api/requests/crdbs/upgrade/

[kaitlynmichael]

LGTM after a few small changes