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.
Backblaze B2 Synology Reddit
Make Backblaze B2 your Cloud Sync destination on your Synology NAS and save up to 75% versus Amazon S3 when you sync your data from your Syno. I just tried setting up B2 with fully patched DSM 6.1.3-15152 U3 and Cloud Sync 2.3.3-0978. It fails with 'unknown errors'. BackBlaze support insists that the issue is on Synology's side. How do I setup a one way sync to B2? Is this a known issue? It doesn't appear that Synology works with B2 right now. Backblaze B2 is part of the Cantemo Achive Framework. This means the Cantemo Portal can enable sophisticated rules to automatically archive or restore an asset or collection to/from Backblaze B2.
Backblaze B2 Vs Synology C2
Synology Cloud Backup
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.