SeaweedFS Cluster Setup Guide

README.md

Configuring Replication at Startup

When you start the master server, you can specify the replication strategy using the -defaultReplication flag. This flag defines how data is replicated across the cluster. Here's how you can set it:

• 000: no replication
• 001: replicate once on the same rack
• 010: replicate once on a different rack, but same data center
• 100: replicate once on a different data center
• 200: replicate twice on two different data center
• 110: replicate once on a different rack, and once on a different data center

For example, if you want each file to have two replicas across the three nodes, you would set the replication strategy to 002. Adjust your master command in the Docker Compose file on each node like this:

command: "master -ip=node01 -peers=node01:9333,node02:9333,node03:9333 -defaultReplication=002"

Changing Replication after Setup

If you need to adjust replication settings after the cluster is up and running, you can either restart the master with new parameters, or use filer to set replication rules for different buckets or directories. Here’s how you might specify replication using the filer's REST API or through its directory structure:

• You can define custom replication rules for specific directories by creating or modifying the .buckets file inside a directory managed by SeaweedFS. This allows different directories to have different replication settings.
• The filer also supports adjusting replication through its API by specifying replication parameters when you create or modify files.

Example

To apply a custom replication rule for a specific directory after the cluster has started, you might do something like this:

Creating a Bucket with Custom Replication:

Use the filer to create a directory and specify a custom replication strategy:

curl -X PUT "http://node01:8888/path/to/directory?replication=002"

This sets the directory to replicate data across nodes using the 002 strategy.

Docker Swarm Notes:

https://github.com/seaweedfs/seaweedfs/wiki/SeaweedFS-in-Docker-Swarm

docker-compose.yml

version: '3.7'
services:
  master:
    image: chrislusf/seaweedfs:latest  # Use the latest SeaweedFS image -defaultReplication=001 
    network_mode: host
    ports:
      - "9333:9333"  # Port for master server 
    command: "master -ip=${HOST} -port=9333 -mdir=/data -volumeSizeLimitMB=1024 -garbageThreshold=0.01 -peers=node01:9333,node02:9333,node03:9333"
    volumes:
      - "./data/master:/data:rw"  # Persist data

  volume:
    image: chrislusf/seaweedfs:latest
    network_mode: host
    ports:
      - "8080:8080"  # Port for volume server
    command: "volume -ip=${HOST} -port=8080 -dir=/data -mserver=node01:9333,node02:9333,node03:9333 -dataCenter=dc1"
    depends_on:
      - master
    volumes:
      - "./data/volume:/data:rw"

  filer:
    image: chrislusf/seaweedfs:latest
    network_mode: host
    ports:
      - "8888:8888"  # Port for filer
    command: "filer -ip=${HOST} -port=8888 -ui.deleteDir=false -maxMB=4 -downloadMaxMBps=100 -master=node01:9333,node02:9333,node03:9333"
    depends_on:
      - master
    volumes:
      - "./data/filer:/data:rw"