139 lines
2.1 KiB
Markdown
139 lines
2.1 KiB
Markdown
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# ASL/STORE-LAYOUT/1 -- On-Disk Store Layout
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Status: Draft
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Owner: Architecture
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Version: 0.1.0
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SoT: No
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Last Updated: 2026-01-17
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Tags: [ops, store, layout, filesystem]
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**Document ID:** `ASL/STORE-LAYOUT/1`
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**Layer:** O2 -- Operational layout profile
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**Depends on (normative):**
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* `ASL-STORE-INDEX`
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**Informative references:**
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* `ASL/HOST/1`
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---
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## 0. Conventions
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The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHOULD**, and **MAY** are to be interpreted as in RFC 2119.
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ASL/STORE-LAYOUT/1 defines a recommended filesystem layout for an ASL store. It does not define semantic behavior.
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---
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## 1. Purpose
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Provide a practical, POSIX-friendly on-disk layout that preserves ASL store semantics while remaining compatible with ZFS or other backends.
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---
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## 2. Minimum Required Components (Informative)
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An ASL store requires:
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* Immutable blocks
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* Append-only log
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* Sealed snapshots
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* Deterministic replay
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Directory layout is an implementation choice. This document defines a recommended layout.
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---
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## 3. Recommended Domain Layout
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Per domain, use:
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```
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/asl/domains/<domain-id>/
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meta/
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blocks/
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index/
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log/
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snapshots/
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tmp/
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```
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All paths are domain-local.
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---
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## 4. Blocks
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```
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blocks/
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open/
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blk_<uuid>.tmp
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sealed/
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00/
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<blockid>.blk
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ff/
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<blockid>.blk
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```
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Rules:
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* Open blocks are never visible.
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* Sealed blocks are immutable.
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* Sealed blocks are sharded by prefix for filesystem scalability.
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---
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## 5. Index Segments
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```
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index/
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shard-000/
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segment-0001.idx
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segment-0002.idx
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bloom.bin
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shard-001/
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...
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```
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Rules:
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* Segments are append-only while open.
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* Sealed segments are immutable and log-visible.
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* Shards are deterministic per snapshot.
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---
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## 6. Log and Snapshots
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```
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log/
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asl.log
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snapshots/
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<snapshot-id>/
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```
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Rules:
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* Log is append-only.
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* Snapshots pin index and block state for replay.
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---
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## 7. Temporary and Metadata Paths
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* `tmp/` is for transient files only.
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* `meta/` contains domain metadata (DAM, policy, host state).
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---
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## 8. Non-Goals
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ASL/STORE-LAYOUT/1 does not define:
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* Device selection or mount options
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* Snapshot mechanism (ZFS vs other)
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* Encryption or key management
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