Files
seaweedfs/seaweed-volume
6ebc055a94 master, volume, filer: start on a read-only mounted directory and serve existing data read-only (#12081)
* master, volume, filer: start on a read-only mounted directory and serve existing data read-only

A read-only mount was treated as writable (permission bits only), so every
service failed on its first write: the master panicked writing raft conf.tmp,
the filer exited opening the leveldb LOCK, and the volume server skipped every
volume while still offering the directory as free capacity.

- util.IsReadOnlyMount: access(W_OK) == EROFS.
- volume: on a read-only -dir take the existing O_RDONLY/noWriteOrDelete load,
  index .idx in memory when no .sdx exists, offer no free slots (same branches
  as isDiskSpaceLow), skip the vid stamp there.
- master: on a read-only -mdir run raft from a private copy and refuse new
  volume ids.
- filer: leveldb2/leveldb3 set their existing ReadOnly option.

* volume: skip read-only mounts when picking EC shard copy targets

A shard copy landing on a read-only mount fails at write time; offer
only writable locations like the other placement paths do.

* volume: mirror the read-only mount handling in the Rust volume server

The .dat open only fell back to read-only on EACCES, so a real read-only
mount (EROFS) still failed the load. The index side already degrades
once no_write_or_delete is set. Add is_read_only_mount via access(W_OK)
== EROFS, mark DiskLocation.read_only_mount, and mirror the Go checks:
no free slots, heartbeat max = used, no vid-stamp writes, no EC shard
copy targets, and a read-only index dir forces the volume read-only.

* volume: write vid stamps while only the index dir is read-only

* filer: skip the write-bit check when a leveldb store opens read-only

* filer: serve reads of buckets with no leveldb3 dir on a read-only store

* volume: derive a stable dir uuid when a read-only mount cannot store one

* master: keep the read-only raft copy across restarts so votes survive

* volume: index a missing .idx in memory on a read-only mount

* volume: release the .idx handle after an in-memory read-only load

* volume: mount EC shards read-only when their index dir is on a read-only mount

* volume: mark the index dir read-only before the tail repair opens .idx

* volume: write vid stamps while only the index dir is read-only (Rust)

* volume: derive a stable dir uuid and report no free slots on a read-only mount (Rust)

* volume: index a missing .idx in memory on a read-only mount (Rust)

* volume: refuse an EC copy whose shard owner is on a read-only disk

* master: key the read-only raft copy by the absolute -mdir

Two masters sharing the same relative -mdir text from different working
directories would have collided on one temp copy and shared raft state.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* volume: mix device and host into the read-only dir uuid

Deriving the uuid from the path alone let independent servers at the
same mount point report one uuid, which RegisterUuids rejects. Hash in
the device id and hostname so restarts stay stable but disks differ.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

---------

Co-authored-by: vic6996-web <320442181+vic6996-web@users.noreply.github.com>
Co-authored-by: user.email <chrislusf@users.noreply.github.com>
Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
2026-10-26 09:28:49 -07:00
..

SeaweedFS Volume Server (Rust)

A drop-in replacement for the SeaweedFS Go volume server, rewritten in Rust. It uses binary-compatible storage formats (.dat, .idx, .vif) and speaks the same HTTP and gRPC protocols, so it works with an unmodified Go master server.

Building

Requires Rust 1.91.1+ (2024 edition), matching rust-version in Cargo.toml. The patch release matters: 1.91.0 does not build. The edition itself only needs 1.85; the higher floor comes from the dependency tree — chiefly the AWS SDK — so it moves with those crates. CI builds on the latest stable.

cd seaweed-volume
cargo build --release

The binary is produced at target/release/seaweed-volume.

Running

Start a Go master server first, then point the Rust volume server at it:

# Minimal
seaweed-volume --port 8080 --master localhost:9333 --dir /data/vol1 --max 7

# Multiple data directories
seaweed-volume --port 8080 --master localhost:9333 \
  --dir /mnt/ssd1,/mnt/ssd2 --max 100,100 --disk ssd

# With datacenter/rack topology
seaweed-volume --port 8080 --master localhost:9333 --dir /data/vol1 --max 7 \
  --dataCenter dc1 --rack rack1

# With JWT authentication
seaweed-volume --port 8080 --master localhost:9333 --dir /data/vol1 --max 7 \
  --securityFile /etc/seaweedfs/security.toml

# With TLS (configured in security.toml via [https.volume] and [grpc.volume] sections)
seaweed-volume --port 8080 --master localhost:9333 --dir /data/vol1 --max 7 \
  --securityFile /etc/seaweedfs/security.toml

Common flags

Flag Default Description
--port 8080 HTTP listen port
--port.grpc port+10000 gRPC listen port
--master localhost:9333 Comma-separated master server addresses
--dir /tmp Comma-separated data directories
--max 8 Max volumes per directory (comma-separated)
--ip auto-detect Server IP / identifier
--ip.bind same as --ip Bind address
--dataCenter Datacenter name
--rack Rack name
--disk Disk type tag: hdd, ssd, or custom
--index memory Needle map type: memory, leveldb, leveldbMedium, leveldbLarge
--readMode proxy Non-local read mode: local, proxy, redirect
--fileSizeLimitMB 256 Max upload file size
--minFreeSpace 1 (percent) Min free disk space before marking volumes read-only
--securityFile Path to security.toml for JWT keys and TLS certs
--metricsPort 0 (disabled) Prometheus metrics endpoint port
--whiteList Comma-separated IPs with write permission
--preStopSeconds 10 Graceful drain period before shutdown
--compactionMBps 0 (unlimited) Compaction I/O rate limit
--compactionMaxParallelCommits 0 (unlimited) Max concurrent vacuum commits
--pprof false Enable pprof HTTP handlers

Set RUST_LOG=debug (or trace, info, warn) for log level control.

Durable (fsync=true) uploads always go through per-volume batching workers that share one .dat/.idx sync per batch, matching the Go volume server; non-fsync writes take the synchronous path.

Features

  • Binary compatible -- reads and writes the same .dat/.idx/.vif files as the Go server; seamless migration with no data conversion.
  • HTTP + gRPC -- full implementation of the volume server HTTP API and all gRPC RPCs including streaming operations (copy, tail, incremental copy, vacuum).
  • Master heartbeat -- bidirectional streaming heartbeat with the Go master server; volume and EC shard registration, leader failover, graceful shutdown deregistration.
  • JWT authentication -- signing key configuration via security.toml with token source precedence (query > header > cookie), file_id claims validation, and separate read/write keys.
  • TLS -- HTTPS for the HTTP API and mTLS for gRPC, configured through security.toml.
  • Erasure coding -- Reed-Solomon EC shard management: mount/unmount, read, rebuild, copy, delete, and shard-to-volume reconstruction.
  • S3 remote storage -- FetchAndWriteNeedle reads from any S3-compatible backend (AWS, MinIO, Wasabi, Backblaze, etc.) and writes locally. Supports VolumeTierMoveDatToRemote/FromRemote for tiered storage.
  • Needle map backends -- in-memory HashMap, LevelDB (via rusty-leveldb), or redb (pure Rust disk-backed) needle maps.
  • Image processing -- on-the-fly resize/crop, JPEG EXIF orientation auto-fix, WebP support.
  • Streaming reads -- large files (>1MB) are streamed via spawn_blocking to avoid blocking the async runtime.
  • Auto-compression -- compressible file types (text, JSON, CSS, JS, SVG, etc.) are gzip-compressed on upload.
  • Prometheus metrics -- counters, histograms, and gauges exported at a dedicated metrics port; optional push gateway support.
  • Graceful shutdown -- SIGINT/SIGTERM handling with configurable preStopSeconds drain period.

Testing

Rust unit tests

cd seaweed-volume
cargo test

Go integration tests

The Go test suite can target either the Go or Rust volume server via the VOLUME_SERVER_IMPL environment variable:

# Run all HTTP + gRPC integration tests against the Rust server
VOLUME_SERVER_IMPL=rust go test -v -count=1 -timeout 1200s \
  ./test/volume_server/grpc/... ./test/volume_server/http/...

# Run a single test
VOLUME_SERVER_IMPL=rust go test -v -count=1 -timeout 60s \
  -run "TestName" ./test/volume_server/http/...

# Run S3 remote storage tests
VOLUME_SERVER_IMPL=rust go test -v -count=1 -timeout 180s \
  -run "TestFetchAndWriteNeedle" ./test/volume_server/grpc/...

Load testing

A load test harness is available at test/volume_server/loadtest/. See that directory for usage instructions and scenarios.

Architecture

The server runs three listeners concurrently:

  • HTTP (Axum 0.7) -- admin and public routers for file upload/download, status, and stats endpoints.
  • gRPC (Tonic 0.12) -- all VolumeServer RPCs from the SeaweedFS protobuf definition.
  • Metrics (optional) -- Prometheus scrape endpoint on a separate port.

Key source modules:

Path Description
src/main.rs Entry point, server startup, signal handling
src/config.rs CLI parsing and configuration resolution
src/server/volume_server.rs HTTP router setup and middleware
src/server/handlers.rs HTTP request handlers (read, write, delete, status)
src/server/grpc_server.rs gRPC service implementation
src/server/heartbeat.rs Master heartbeat loop
src/storage/volume.rs Volume read/write/delete logic
src/storage/needle.rs Needle (file entry) serialization
src/storage/store.rs Multi-volume store management
src/security.rs JWT validation and IP whitelist guard
src/remote_storage/ S3 remote storage backend

See DEV_PLAN.md for the full development history and feature checklist.