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openstack-caracal-dc-dc / docs / changelog-20260709-dc-dc-design.md

Changelog 2026-07-09 -- DC-DC (VR1) originating design

Delivery from the main-chat DC-DC planning stream. Grounded on openstack-caracal-dc-dc HEAD 8813efc (seed-verified). All decisions PROPOSED -- this is a design/plan deliverable, not an implementation. Under blanket approval this changelog is the review surface: what, why (evidence), and how to revert, per item.

Items

  1. ADD docs/dc-dc-buildout-design.md -- originating buildout design for the virtual regional two-DC test env (VR1), Phase 0-6 spine, gates, D-refs, shim register, DR drill skeleton, host/disk/MTU plan. Why: the mission deliverable; no prior DC-DC design doc existed. Revert: delete the file.

  2. ADD docs/dc-dc-D100-D110.append.md -- append fragment carrying PROPOSED decisions D-100..D-110 for concatenation onto docs/design-decisions.md. Why: encodes the settled DC-DC inputs as append-only D-entries; fragment (not direct edit of design-decisions.md) keeps the overlay a clean documented append. Revert: delete the fragment; if already appended to design-decisions.md, remove the D-100..D-110 block (append-only, so a tail trim) and re-run ledger-scan.

Grounded corrections captured (not silent)

  • D-052 "metal-internal may-cross-fiber" refined to DC-local for the independent-cloud topology (only replication crosses). Evidence: D-052 text (stretched-cloud assumption) + independent-Keystones topology.
  • D-057 provider-vip plane NOT carried -- reverted by D-060 (Pattern A). Only the root-cause br-ex discipline is carried. Evidence: D-057 live status header.
  • DR-seed v4 replication carrier (10.12.36.0/22) superseded -> IPv6-only ULA. Evidence: operator ruling + D-101 family matrix.
  • No IPv6 literals hardcoded -- ULA /48, per-DC GUA carve, DC2 v4 supernet are NetBox-authoritative. Evidence: repo grep found no committed authoritative literals.

Landing (operator)

Per docs/dc-dc-buildout-design.md Section 11: append the fragment to design-decisions.md, run ledger-scan.sh (expect D next-free 111), add a main-chat ledger-fence line, repo-lint.sh (ignore >099 next-free noise), commit.

Open for redline

Ceph size=3 vs documented size=2 fallback (Phase-0 disk math); netem link profile; D-102/D-101 merge; D-109 standalone; metal-admin ULA leg; COS roll-up; mirror sync topology. See design doc Section 10.