docs: fold HNSW snapshots into concepts/storage for v1.39

[g-despot]

Follow-up to #475, applying the review feedback on it.

What changed, and why the page is gone rather than moved

The feedback suggested moving configuration/hnsw-snapshots into the Storage and Backups section, on the grounds that there is not much to configure now. Taking that a step further: in v1.39 there is nothing to configure at all, so the page no longer earns its own URL. Its content is folded into the storage concepts page, and the per-variable reference stays in the env-vars table — which already documented all five variables in full, defaults included, so most of the deleted page was duplicating it.

Net effect: the pre-v1.39 material drops from ~40 lines of a 63-line standalone page to ~9 lines on the concepts page, half of that behind a <details>, with no TOC entry, no sidebar entry and no card. That addresses the "documents too much the historical approach" half of the feedback, which simply relocating the page would not have.

The old URL 301s to /weaviate/concepts/storage#hnsw-snapshots. That redirect is load-bearing: the 1.31 release blog hardcodes the old path, and there is a live kapa answer citing it.

The alarmist framing

The "Snapshots are now required to start" caution is replaced with plain prose covering the checksummed block format, the write-then-delete ordering, and the commit logs on disk being the delta since the last snapshot.

One correction in the other direction, though: the original text understated the blast radius. An unreadable snapshot fails the whole shard, not just the one vector index — one bad named vector aborts every vector index on that shard. Whether the node survives depends on how the shard loads, and the first draft of this PR got that backwards, so to be explicit: lazy-loaded shards leave the node up and return errors per request, eagerly loaded shards fail node startup, and eager is the default for single-tenant collections and for multi-tenant collections below the auto-detection thresholds. Being accurate here reads as less alarming than the caution box did, not more.

Are there any new env vars? — No

Checked against core on the 1.39 line. The compact package reads no environment variables at all; every compactor tunable is a hardcoded Go default (MaxFilesPerMerge, SnapshotThreshold, block size, buffer sizes). The only related knob that still does anything is the pre-existing PERSISTENCE_HNSW_MAX_LOG_SIZE, which paces WAL rotation rather than configuring snapshots.

Two places the suggested wording didn't survive contact with the code

Flagging these rather than burying them, since both came from the review:

1. "the snapshot format being more efficient than the commit logger." The V3 snapshot format predates v1.39 — the migrator moves an existing V3 snapshot byte-for-byte on upgrade. So the disk-usage win is not a new format. It is (a) no duplication, since earlier versions keep the full commit log alongside the snapshot, and (b) compaction keeping only the final state of each vector's connections rather than every change. The page now says that instead.

2. "the commit logs now just store the delta." True as an outcome, but there is no delta encoding. The logs a snapshot covers are deleted once it commits, and older ones are filtered out at replay, so what remains on disk is the delta. Written as the mechanism, since "the commit log format changed" would be wrong.

The disk-reduction note also carries three qualifiers, because it is not realised at the upgrade instant: it appears after the compactor's first cycles on each loaded shard, inactive tenants do not shrink until next activated, and peak usage still rises while a snapshot is being written — so it is not a reason to cut disk headroom. No numbers published.

Two changes outside the stated scope

Easy to drop if you'd rather keep the diff tight:

• storage.md vector-cache link. Fixes a broken anchor that had been reported as "pre-existing" for a while. APITable sets each row's id to the variable name verbatim, so the link needs upper case. Worth knowing generally — onBrokenAnchors is not configured in this repo, so wrong-case anchors warn rather than fail and tend to accumulate.
• The weaviate.conf.json sentence names the --config-file flag and the camelCase field shape. Without that it was unusable: it said "the same settings", but the field names are not the same (hnswDisableSnapshots, not PERSISTENCE_HNSW_DISABLE_SNAPSHOTS), so a reader grepping their config file would find nothing and conclude they were unaffected. Note this path is also silent — env vars log a deprecation warning at startup, config-file fields are accepted and ignored with none. That file is documented nowhere in this repo; tracked separately.

Implementation note

The {#pre-v1-39-configuration} anchor sits on the heading above the <details>, not inside it. Docusaurus's Details component has no hashchange or location-hash handling and only toggles on summary click, so an anchor inside would strand the five inbound env-var links on a collapsed summary. It also renders with lazy={false}, so the collapsed content is in the built DOM — meaning a "is the anchor in the HTML?" check passes even when the anchor is unreachable.

Verification

yarn build and yarn build-dev both pass. validate-links-pr.js reports only the googletagmanager URL that needs GOOGLE_CONTAINER_ID, which is not available locally. All five retargeted env-var deep links resolve, both anchors confirmed outside the collapsible in the built HTML, and the redirect was checked against preceding wildcards for shadowing.

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Secrets	0   0   0   0	View in Orca

[Copilot]

Pull request overview

This PR updates the Weaviate docs for v1.39 by removing the now-obsolete standalone “HNSW snapshots” configuration page and folding the relevant conceptual + historical (pre-v1.39) information into the Storage concepts page, while preserving compatibility via redirects and updated deep links from the env-var reference.

Changes:

• Remove the weaviate/configuration/hnsw-snapshots page from navigation (sidebar + configuration landing cards) and delete the standalone doc.
• Expand weaviate/concepts/storage to include the v1.39 snapshot/compaction model plus a condensed, anchored pre-v1.39 configuration section.
• Update references and routing: add a Netlify redirect from the old URL and retarget env-var deep links (plus a related-page link from persistence docs).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
sidebars.js	Removes the HNSW snapshots page from the configuration sidebar navigation.
netlify.toml	Adds a 301 redirect from the removed configuration URL to the new anchor on the storage concepts page.
docs/weaviate/configuration/index.mdx	Removes the “HNSW Snapshots” configuration card from the configuration landing page.
docs/weaviate/configuration/hnsw-snapshots.md	Deletes the standalone HNSW snapshots configuration page (content moved/condensed elsewhere).
docs/weaviate/concepts/storage.md	Incorporates HNSW snapshots content (v1.39 behavior + pre-v1.39 details under a stable anchor).
docs/deploy/configuration/persistence.md	Adds a related link pointing readers to the new HNSW snapshots section in storage concepts.
docs/deploy/configuration/env-vars/index.md	Retargets deprecated snapshot env-var rows to the new pre-v1.39 anchor on the storage concepts page.

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