Tao of Mac

Feb 24th 2017 · 1 min read · #apps #dropbox #file #synchronization #syncthing

SyncThing ➹

SyncThing is a cross-platform, open source file synchronization tool that I’ve been using for a while now to keep my files in sync across all my devices.

Tuning

Hacks I did to the config.xml file to lower impact on my Synology NAS, which the WebUI promptly reverted upon the first time I used it:

<!-- under the main options -->
<maxHashingThreads>1</maxHashingThreads>
<maxFolderConcurrency>1</maxFolderConcurrency>
<maxConcurrentScans>1</maxConcurrentScans>
<progressUpdateIntervalS>5</progressUpdateIntervalS>

<pullerMaxPendingKiB>1024</pullerMaxPendingKiB>
<disableTempIndexes>true</disableTempIndexes>
<fsWatcherEnabled>true</fsWatcherEnabled>
<fsWatcherDelayS>10</fsWatcherDelayS>

<!-- For each folder -->
<minDiskFree unit="%">1</minDiskFree>
<copiers>1</copiers>
<pullers>1</pullers>
<hashers>1</hashers>

These had very limited effect in CPU usage, unfortunately. What did help significantly was to set most of the folders as receive-only and to rescan daily or weekly instead of the default, since I never modify files directly on the NAS.

For constrained systems, I also deploy it in a tuned systemd unit:

[Unit]
Description=Syncthing - Open Source Continuous File Synchronization
Documentation=man:syncthing(1)
StartLimitIntervalSec=60
StartLimitBurst=4

[Service]
ExecStart=/usr/bin/syncthing serve --no-browser --no-restart --logflags=0
Restart=on-failure
RestartSec=1
SuccessExitStatus=3 4
RestartForceExitStatus=3 4

# Hardening
SystemCallArchitectures=native
MemoryDenyWriteExecute=true
NoNewPrivileges=true

# Strict resource limits
CPUQuota=5%
MemoryLimit=512M
LimitCORE=1

# Elevated permissions to sync ownership (disabled by default),
# see https://docs.syncthing.net/advanced/folder-sync-ownership
#AmbientCapabilities=CAP_CHOWN CAP_FOWNER

[Install]
WantedBy=default.target

This is how I run it on my NAS, with minor alterations:

---
version: "3"
services:
  syncthing:
    image: syncthing/syncthing:latest
    container_name: syncthing
    hostname: diskstation
    environment:
      - PUID=1024
      - PGID=100
      - TZ=Europe/Lisbon
      - HOME=/var/syncthing/config
      - STGUIADDRESS=0.0.0.0:8384
      - GOMAXPROCS=1
    volumes:
      - /volume1/homes/user:/home/user
      - /volume1/docker/syncthing/user:/var/syncthing/config
    network_mode: host
    restart: unless-stopped
    cpuset: "0" 
    cpu_shares: 2
    healthcheck:
      test: curl -fkLsS -m 2 127.0.0.1:8384/rest/noauth/health | grep -o --color=never OK || exit 1
      interval: 1m
      timeout: 10s
      retries: 3

Resources

Category Date Link Notes
Clients 2020 MobiusSync

The iOS client I’ve been using with it
Documentation 2021 Tuning

Tuning Guide1