Sync Obsidian Across Devices for Free via a Synology NAS

I wish I wasn’t as particular as I am, but not much to be done about that. If I want a thing, it will be thoroughly researched and I will obtain the perfect thing that suits my needs. And I don’t mean to say the perfect thing is necessarily expensive or literally the best available version of the thing I’m looking for, but that it checks all the boxes I’ve arbitrarily decided are important for the thing. Either way, I get hung up on the thing.

I’ve used at least a dozen different note-taking, Personal Knowledge Management, Project Management and productivity apps and software over the years. I used to be all about Evernote until they shit the bed, and ever since I’ve been free-floating through the Internet occasionally testing out a cool new note-taking app or self-hosting some novel new PKM software suite.

I don’t know if there’s a best one, and there certainly isn’t one that will ever check every single box for me. I’ve kind of landed on a 3-prong approach of:

1. TickTick for tasks and reminders (I’m considering trying out Google Tasks again for the simplicity and Google Assistant integration, but as soon as I dive in I’m sure they’ll add it to the Google Graveyard)
2. Google Keep for quick notes and the occasional reminder
3. Obsidian for in-depth notes, data and some very light project management

Obsidian is an interesting one. I’ve come across it dozens of times when I inevitably search for “best note-taking app.” I’ve even downloaded it a few times to test it out, often resulting in me giving up until the next time I Google “notes? what are? how do?”

I’ve decided to a real attempt at learning and using Obsidian. It’s daunting, but as I’m getting into it, I’m realizing that it’s not nearly as difficult as I originally thought. Markdown always freaked me out a bit – I’d think, I don’t want to have to learn some new writing format just to jot down my grocery list or keep track of my list of Red Dead Redemption 2 collectibles. But having used it, and making some strong use out of the various community plugins, I’ve gotten the hang of it, at least as far as my own personal use goes.

What I did actually find annoying was the lack of a cross-device sync, at least for free. Obsidian does offer this service as a paid $4/month option, but I’m cheap and don’t want to.

Obsidian isn’t truly self-hosted, but it sort of is in the fact that your data lives as plain ol’ text files on whatever device you’re using. People tend to use services like Syncthing or Dropsync to sync their Obsidian vault (the folder where your files live) from one device to a cloud storage service, then sync it to a second device with another sync service. This feels cumbersome to me, and much like Alton Brown’s hatred of uni-task kitchen tools, I really hate signing up for more new services and tools when I don’t have to.

I have a NAS, a Synology DS920+ mainly used as a media server with a handful of network monitoring tools running as well (one day I’ll build a proper homelab…). Synology also offers a built-in sync tool that syncs data between multiple devices, much like Dropsync, as well as some cloud backup tools. All of this runs on a single account and is directly connected to the file system on my NAS. I'd imagine that other NAS manufacturers like QNAP or ASUSTOR probably have similar tools available, and I assume that something could be rigged up if you're running an open-source NAS OS like TrueNAS or UnRAID.

So here is the setup:

1. Obsidian is installed on my PC.
2. My Obsidian vault is saved to a network-mapped folder on my NAS.
   • This is a folder on that lives on the NAS that acts as though it’s local to the PC, just like C: or a USB drive. Here are some instructions.
   • If I take add anything to Obsidian, it saves directly to this folder, so it bypasses my local PC storage and saves directly to the NAS.
3. Obsidian is installed on my phone.
   • I created an Obsidian folder on my phone and set this as the vault folder for the app.
4. The Synology Drive app is installed on my phone.
   • I set up a two-way sync task in Synology Drive to sync the contents of the Obsidian folder on my phone to the corresponding folder on my NAS.

That’s basically it. When a file is changed or added by Obsidian on my PC, it is immediately saved to my NAS, then syncs to my phone via Synology Drive (and additionally backed up to a separate cloud storage service via Synology Cloud Sync) and is accessible when I open the Obsidian app. Then the same thing, but backwards, occurs when a file is created or changed on my phone.

While not quite “free” in the sense that the DS920+ and it’s accompanying goodies were certainly not cheap, this uses equipment I already had and with no additional services to sign up for or subscribe to, with an added bonus of easy backups.

This same process can be set up for any other phone-to-Synology sync tasks as well. I'm using this to sync my Tasker and 2FA app settings to my NAS (and from here to some cloud storage) as a backup solution. I'd imagine there are some other clever uses as well.

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