My current production box is OMV4 and I back it up to an external USB drive and offsite to B2 Cloud Storage via Duplicati. I have nearly 1 TB on B2 and it's extremely inexpensive.
At work, I have a large Synology with about 8TB of media that I also backup to B2 using the built in cloud backup program on the Synology. The Synology program backs up the individual files on B2 and if need to grab a file off of B2 - it's as easy as logging into the website and downloading the file.
With Duplicati - a restore must be done from within the web interface of Duplicate itself as the backup sets are useless without the Duplicati program and database to run the restore. In the event of a total disaster and loss of the server, and usb backup, I fear how difficult a disaster recovery would be. All I would have would be 1 TB of data sets - without the original server.
As I'm building a new OMV5 box, I wanted to re-examine my backup procedures and see if there was a backup program for OMV5 data that works as nicely as the Synology Cloud Backup - giving you actual files in B2 rather than "backup sets." I'm sure the backups would be bigger and might take longer, but I think the backups would also be more usable and user friendly.
Thanks for your suggestions.