Synology Active Backup Backblaze
Synology® Cloud Sync now supports Backblaze B2 Cloud Storage Bellevue, WA—July 7, 2016—Synology ® Inc. Today announced its top rated file syncing and backup application Cloud Sync now supports B2 Cloud Storage, an increasingly popular and competitively priced cloud storage service from Backblaze. Backblaze B2 is a recently released cloud backup storage solution that works with Synology NAS (and other applications). It charges $0.005 per GB to backup; this works out at around $5 for 1TB. By far the cheapest cloud storage solution compared to others, finally making it affordable for to use this type of solution.
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.
Synology Hyper Backup Azure
Synology Windows Backup Software
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.