Backup and synchronization of an android phone, NAS, and desktop.

I’m hoping someone can help me with the setup of my backup and synchronization I am attempting to setup. What I want to do is a one-way send-only backup of the photos and videos from 2 android devices into a folder on my NAS. If possible, I don’t want this one way backup to sync a deleting of files that might take place on the android phones. Thus, any files sent from the android phones, remain on the NAS folder even if they are deleted from the android phones. The NAS folder where I want to send these photo and video files, already contains photo and video files from different phones I’ve had over several years. The first problem I ran into with this setup, is that syncthing asked for an override for the files on the NAS folder to be deleted that don’t exist on my 1st of two android devices I am attempting to backup. In other words, synching was asking to delete the photos and videos on my NAS folder from my old devices. If possible, I want to continue using this one NAS folder as storage for photos and videos for old, current, and future phones.

Secondly, I then want to synchronize that single NAS folder with a folder on my desktop computer. This step I was able to setup with no problem. I have the desktop and NAS folder set to a send/receive relationship where any files changes in those folders synchronize with each other. This allows me to have a 2nd local backup of the photos and videos from my phones.

Thanks in advance for any help you can provide.

There are ways to do what you want with Syncthing but it’s more or less a hack rather than the intended way to use the software. Syncthing is a two-way “continuous file synchronization program”, not a backup tool to transfer files in a single direction. You will probably still find what you want if you check the configuration-related information in the Docs, especially the advanced part.

Just for clarification though, what you’re explaining above sounds more like having redundant copies (like disks connected in RAID1 in case one of them fails) rather than a proper backup solution. This is because with Syncthing, if you delete or modify a file on one side, the changes will almost immediately propagate to other devices, meaning that the “backup” may be lost very quickly.

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Thank you for your reply. I have a redundant offsite backup through backblaze in case there is any data loss with my computer hard drive or my NAS. I also have trashcan file versioning enabled in case there is an error with synchronization. I do prefer to having the hard drive and NAS in a sync relationship, so files deleted or modified on the computer are synchronized to the NAS. I’ll try reviewing the Docs again, but I had a hard time trying to find specific settings that would accomplish what I am trying to do where I have only a one way backup from my phones to my NAS with no ability for files to be deleted on my NAS based on any changes to files on the phones.

Syncthing is fundamentally a sync tool. You are best off by doing this: On the computer, regularly move photos out of the synced folder.

Wouldn’t moving photos out of the synced folder trigger syncthing to delete those photos from the folder on my phone since it would detect a change in the computer folder from which they were removed and then attempt to synchronize that change to the folder on the phone?

Yes, exactly.