unison VS btrbk

If you look at the release notes you can see that some versions say they are protocol compatible with prior X.Y version release

https://github.com/bcpierce00/unison/releases

You might want to try Unison: https://github.com/bcpierce00/unison

I highly recommend Unison (https://github.com/bcpierce00/unison)

It allows you to sync between 2 machines (bi-directional) over TCP or SSH.

Note that TCP way is not encrypted, you may use wireguard as transport layer encryption for that purpose...

You can use an external application to copy if file size is larger than an arbitrary number. (Eg: use rsync for files > 1gb)

The iOS app only syncs via iCloud or Obsidian Sync. I was in a similar situation (wanted to sync to Linux PCs and iPhone without paying for Sync), but I do have one always on Mac, so I set up a script that runs every minute, syncing my vault on iCloud with an identical vault on Synology Drive. My script basically just runs Unison once every few minutes to keep the two vaults in sync.

Unison is another alternative. I use it to synchronize my music with a Samba share and an usb stick, works great.

Unison

I've tested many file synchronization. I rely via scripts on Unison, originally authored by the computer scientist Benjamin Pierce, and now decades of tweaking by a strong open source community.

https://github.com/bcpierce00/unison

I'd love to see Darke Files get everything right that Unison gets right, that nearly all commercial projects get wrong, through a blend of arrogance and ignorance:

* Meta data. It takes a lot to insure that two copies of a MacOS file appear identical to a user. There used to be a test suite on the web that embarrassed everybody.

* Atomic folders such as ".git" or an application bundle. A prototypical example is a MacOS disk image, supported by a folder of many small files. This helps minimize incremental backup and transfer. Unison lets you specify the conflict resolution at the folder level, all-or-nothing decide which copy or fix it.

* Symbolic links. This is wildly complicated by users, sure they're right, who want special handling to hack features into sync software that isn't there. A symbolic link is just a file, with correct use the responsibility of the user. You wouldn't want sync software stopping to view your porn, right? They're just files, not the sync software's business.

I use Dropbox for various purposes because I need to, but they bungle more of this than one would expect. For example, a typical MacOS application bundle can have internal symbolic links a typical user never notices, pointing the "current" version of resources to a versioned folder. Last I checked, Dropbox expands the symbolic link into a redundant copy, wasting space without kneecapping the app.

One could go on...

I've been using Unison [1] to sync two and more computers for years. I can't recommend it enough.

[1]: https://github.com/bcpierce00/unison

That's still easier using snapshots and something like btrbk. Snapshot the directory at start, prune if there are too many snapshots (or snapshots get too old).

I'm on Arch, but you might still find it useful: Btrfs snapshots Arch Wiki - Incremental backup to external drive GitHub - btrbk

the smoothest backup tool i have seen for Linux is btrbk works real nice and is customizable for almost all use-cases BTRFS rocks :)

I recommend redundancy and regular verification is you want to insure your data against corruption. If you do that, you can forget about things like ECC. My setup is a NUC server running Ubuntu with a USB3-connected storage drive running BTRFS. I use btrbk to auto-snapshot and auto-replicate via incremental sends to my BTRFS backup drive, and RotKraken to track integrity of the data with a monthly verification run so that I notice corruption in time to correct it.

In pondering my backup strategy, I was wondering if I could use BTRFS snapshots and a backup tool like btrbk, which is a nice integrated snapshot/backup solution I've used happily on desktop Linux. BTRFS needs subvolumes for snapshots, so I couldn't backup the host itself (which wasn't installed with a / subvolume like other distributions I've used), but it could snapshot the VMs and containers, which have their own individual subvolumes. Then btrbk can send that snapshot in an incremental fashion to external storage.

I then installed btrbk and tried to follow the instructions to create snapshots of root and home on the SSD and then send/receive those to the HDD. I mainly used https://github.com/digint/btrbk and https://mutschler.dev/linux/fedora-btrfs-35/, but I don't use luks.

For anyone using btrfs on their system, I heartily recommend btrbk, which has served me very well for making incremental backups with a customizable retention period: https://github.com/digint/btrbk

btrbk is the best solution I know.

I use BTRBK to make and copy the BTRFS snapshots to my HDD. I schedule it to run every 3 hours using a Sytemd unit file through my own script to avoid running the backup at inconvenient moments: