nbd-rs

Network Block Device Server written in Rust. Currently in alpha stage. See Disclaimer.

Why?

Main purpose of this project is to explore possibilities around network block storage, using the capabilities of NBD Protocol, but beyond the capabilities of nbd-server. Some of the extended features are:

• Pluggable backends (Block: Raw, Sharded, Distributed Object: File, S3)
• Chainable backends (i.e. Cache, Retry)
• Memory-safety & Race-free NBD Server implementation, thanks to Rust

Disclaimer

DO NEVER USE THIS FOR PRODUCTION

Do not use this for any data that you cannot afford to lose any moment. Expect data loss, corruption/bit rot, and every other possible storage disaster.

If you use alpha level software for your data, you might end up like we did previously => sheepdog/sheepdog#425

We're learning Rust, don't judge. Help instead.

NOT FEATURES

• You will lose your data if you rely on this alpha software
  • Test it, OK
  • Use it, you will lose your data

Features

See changelog.

• Ability to serve raw images
• Ability to serve chunked volumes (a raw image, split into 4MB chunks)
  • from various (pluggable) backends, currently file and s3 backends are implemented
• Ability to use chainable backends, like cache
• Ability to distributed chunks to multiple backend storages

General Architecture

TODO: Make a graph / drawing

• NBD Server
• -> serves an export(volume)
• -> uses a BlockStorage internally
  • could be a single RAW image (RawStorage)
  • could be a distributed volume (DistributedStorage)
• -> uses an ObjectStorage backend (could be chained)
  • could be a single file (mmap'ed) (FileObjectStorage) file:$(pwd)/raw.bin
  • could be multiple files for DistributedStorage (FileObjectStorage) file:$(pwd)/disk1/chunks/
  • could be S3 for multiple files (S3ObjectStorage) s3://minio:minio@localhost:9000/diskbucket/disk1/chunks/
  • could use CacheStorage for memory cache (chained to something else above) cache+s3://minio:minio@localhost:9000/diskbucket/disk1/chunks/

Build

cargo build

The executable binary is located at ./target/debug/nbd-rs.

Run

Subcommands

nbd-rs init --size <SIZE> <DRIVER> <DRIVER_CFG>
nbd-rs serve --export <EXPORT> <DRIVER> <DRIVER_CFG>
nbd-rs destroy <DRIVER> <DRIVER_CFG>

Simple Example

nbd-rs init --size 100Mi raw "file:$(pwd)/raw.bin"
nbd-rs serve --export mydisk raw "file:$(pwd)/raw.bin"
nbd-rs destroy raw "file:$(pwd)/raw.bin"

Multiple Exports

nbd-rs init --size 100Mi raw "file:$(pwd)/raw.bin"
nbd-rs init --size 200Mi raw "file:$(pwd)/raw2.bin"
nbd-rs serve --export disk0 raw "file:$(pwd)/raw.bin" --export disk1 raw "file:$(pwd)/raw2.bin"
nbd-rs destroy raw "file:$(pwd)/raw.bin"
nbd-rs destroy raw "file:$(pwd)/raw2.bin"

Distributed Example

nbd-rs init --size 2Gi distributed "replicas=3;backends=\
cache:s3:http://usename:password@${S3_HOST}/node0,\
cache:s3:http://usename:password@${S3_HOST}/node1;"

nbd-rs serve --export mydisk distributed "replicas=3;backends=\
cache:s3:http://username:password@${S3_HOST}/node0,\
cache:s3:http://username:password@${S3_HOST}/node1;"

nbd-rs destroy distributed "replicas=3;backends=\
cache:s3:http://username:password@${S3_HOST}/node0,\
cache:s3:http://username:password@${S3_HOST}/node1;"

For more advanced examples please look examples.md.

Contributing

VERY WELCOME! (Contributions to the contribution guide is also very welcome.)

Please see CONTRIBUTING.md

COPYING

GPL-3.0

Copyright 2021, Rainlab Inc. Tokyo and nbd-rs contributors (please see commit history)