Files
seaweedfs/seaweed-volume
Chris Lu 9bafeb6139 ec: refuse to mount a 0-byte shard file when the index has entries (#11030)
* ec: refuse to mount a 0-byte shard file when the index has entries

The startup scan already skips (and eventually deletes) zero-sized shard
files as residue of a failed copy, but the mount RPC path opens the file
directly with no size check, so an explicit VolumeEcShardsMount over a
truncated file registers a size-0 claim. A registered empty shard serves
nothing while advertising ownership: with placement pinned to the owning
disk, it would keep attracting re-copies to a file that was never valid.

The one legitimate 0-byte shard is the empty volume's: encoding a volume
with no live needles produces a 0-byte .ecx and 0-byte shards, and that
mount must keep working (TestMountEcShards_EmptyEcxMountsSuccessfully).
So the gate compares against the index: AddEcVolumeShard (Go) and
EcVolume::add_shard (Rust) refuse a 0-byte shard file only when the
volume's .ecx has entries. Go's AddEcVolumeShard grows an error return
for this; the loader cleans up the refused shard and, when it just
created the EcVolume, unregisters that too. The mount loop already
collects non-ENOENT failures per disk and keeps scanning, so a sibling
disk holding a real copy still wins.

Regression tests in both trees: an empty shard beside an index with
entries is refused and leaves nothing registered; an empty shard of an
empty volume still mounts.

Claude-Session: https://claude.ai/code/session_01AWpefvdi4U3HLng18x5CJ9

* ec: release the duplicate shard when a mount retry re-loads it

Review follow-up: AddEcVolumeShard keeps the existing shard and reports
added=false for a shard this disk already registered, but the loader
discarded that result, so every retried LoadEcShard leaked the duplicate
it had just opened — an fd and a mount-gauge increment per retry. Release
both and return the existing volume. Regression test pins the gauge.

Claude-Session: https://claude.ai/code/session_01AWpefvdi4U3HLng18x5CJ9

* ec: close the test DiskLocation instead of only its EC volumes

Review follow-up: DiskLocation.Close() also stops the background
goroutine NewDiskLocation starts; closeEcVolumes left it running for the
rest of the test process. Both uses are this PR's own tests.

Claude-Session: https://claude.ai/code/session_01AWpefvdi4U3HLng18x5CJ9

* rust: unregister the just-created EcVolume when its first mount is refused

Review follow-up: when the first mount of a volume rejects its shard
(e.g. the new 0-byte-beside-nonempty-index refusal), the Rust mount path
had already inserted the EcVolume and propagated the error without
removing it — a zero-shard registration advertising a mount that serves
no data while pinning the .ecx/.ecj descriptors (and, since placement's
mounted tier keys off it, steering shard placement at this disk). Remove
it on the way out, exactly as the Go loader already does; a volume that
already holds shards keeps them (the RPC's first-error-aborts contract).
Regression test covers both.

Claude-Session: https://claude.ai/code/session_01AWpefvdi4U3HLng18x5CJ9

* rust: skip already mounted shards on a mount retry

Review follow-up: EcVolume::add_shard replaces self.shards[id] for a
shard the volume already holds, and the mount loop then bumps the
ec_shards gauge although the mounted count did not grow — gauge drift on
every mount retry, and a serving fd swapped for no reason. Skip shard
ids the volume already reports, mirroring Go's AddEcVolumeShard
added=false handling. Regression test pins the gauge across a duplicate
mount (unique collection label: the gauge is process-global and tests
run in parallel).

Claude-Session: https://claude.ai/code/session_01AWpefvdi4U3HLng18x5CJ9
2026-08-29 14:19:16 -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 1.75+ (2021 edition).

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
--pprof false Enable pprof HTTP handlers

Set RUST_LOG=debug (or trace, info, warn) for log level control. Set SEAWEED_WRITE_QUEUE=1 to enable batched async write processing.

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.