It depends on the volume of data. Running a second Synology unit at another site and mirroring changes (using something approaching the efficiency of rsync) will easily be the most economical beyond 1tb -- an amount typically included for free with just about every Office 365 subscription. It's not ideal however, unless you plan to perform DR to the cloud; that is, restore a failed local instance to a cloud platform. This is because you will be unable to get one tenth of 1tb of data that stored in the cloud in a timely fashion unless it is being restored to an adjacent platform.

The cool thing about rsync is that the bandwidth use can be near zero as you can do a full mirror once a week but generate a differential file each night and export it to a local drive instead of applying the changes over the internet. That differential file can be used to roll the remote version forward to the time the file was generated. You would only actually apply it to the remote mirror if need be -- testing notwithstanding.

Backblaze Synology Cost

Backblaze For Synology Download

.Sync tools to enable remote user workflows and speed collaboration across multiple locations. A complete, cost-effective 3-2-1 backup protection solution. I use Backblaze B2 to backup my NAS via CloudSync. It’s effortless, works really well, and (though not super cheap) is a pretty good value. I use regular Backblaze Personal to backup my Macs. This isn’t the same as TimeMachine. TM is a MacOS functionality that’s designed to keep constant backups to directly-attached or local network drives.