Data Blob

• *rea:*Data Platform
• *ath:*data/blob
• *ind:*Distributed blob storage substrate (RFC-001)

Role in the stack

kdb-blob é o substrato de armazenamento de objetos para tudo que produz bytes grandes na Stack: uploads, segmentos de mídia transcodificada, backups, snapshots, modelos de ML. Splits content into 4 MB chunks addressed by BLAKE3256, supports range reads, multipart uploads, replication, erasure coding, lifecycle tiers, and an S3compatible gateway.

Deployed as kdb-blob-server (axum, default 0.0.0.0:7400); RUST_LOG controls tracing; Prometheus /metrics available.

Substrate

• *ackend* FsBlobStore (filesystemrooted, contentaddressed). v0.2 swaps to networked backends via the same trait surface.
• *eplication (BLOB
  )* pick_placement chooses N nodes per chunk; production worker (BLOB
  ) drives the actual fan-out.
• *rasure coding (BLOB
  )* ReedSolomon 6+3 for cold tier — 2× space efficiency vs 3× replication while tolerating 3 node losses.
• *ifecycle (BLOB
  )* hot → warm → cold → archive transitions per access pattern. Daemon scheduler queued in BLOB
  .
• *C (BLOB
  )* refcountbased, with grace period before reclaim.
• *crub (BLOB-
  )* daemon walks chunks, verifies BLAKE3, repairs from peers when corruption detected.

Key features

• [x] Singleshot PUT / GET / HEAD / DELETE (BLOB
  #002#003).
• [x] Multipart resumable upload (BLOB-
  ).
• [x] Replication topology (BLOB
  ) + erasure coding (BLOB
  ).
• [x] Lifecycle tiers (BLOB
  ) + GC (BLOB
  ) + scrub/repair (BLOB-
  ).
• [x] S3compatible gateway — ListObjectsV2, SigV4 parsing (BLOB
  ).
• [x] FS backend (BLOB
  ), HTTP server (BLOB
  ), Prometheus + tracing (BLOB-
  /#014).
• [x] GC + scrub daemons (BLOB-
  ).
• [x] Bench harness (BLOB-
  ).
• [x] koder_foundation_util::RateLimiter integration (BLOB-
  ).
• [x] BlobEventSink — PutAccepted / GetServed / ChunkScrubbed / GcSwept / ReplicationLag (BLOB-
  ).
• [x] #[instrument] parity on PUTGETHEAD/DELETE (BLOB-
  ).
• [x] Tenant isolation auth — Bearer token → allowed_tenants (BLOB-
  ).
• [x] Pertenant rate limit on PUT (BLOB
  ).
• [x] Blob size cap (100 GB) + ContentLength validation (BLOB
  ).
• [x] kdb_blob_put_seconds / get_seconds persizebucket histograms (BLOB-
  ).

SLO targets (RFC §SLOs)

• p99 PUT (small blob ≤ 1 MB) ≤ *0 ms*
• p99 GET (cached) ≤ *0 ms*
• Durability: *1 9s*(replication + erasure).
• Availability: *9.99%*(multi-region replication).

Interfaces

• HTTP (Koder native): PUT /v1/{tenant}/blobs/{id}, GET, HEAD, DELETE, /v1/{tenant}/blobs/{id}/head, /healthz, /metrics.
• HTTP (S3compatible): s3compat::list_objects_v2, SigV4 parsing scaffolding (verification queued BLOB
  ).
• Library: kdb_blob::{FsBlobStore, MultipartManager, lifecycle_evaluate, GcLedger, ScrubStats, HttpState, TenantAuth, BlobEventSink}.

Open backlog

4 followups in infra/data/blob/backlog/pending/: pertenant storage quota (BLOB
), SigV4 signature verification (BLOB
), lifecycle daemon scheduler (BLOB
), replication worker fanout (BLOB-
).