How to backup a 7TB Synology Server

It should work, but keep in mind:

1) Your connector type. USB2 for multi TB of data is way too slow .. trust me. I'd ensure you have the e-sata or FW800 (maybe not if your on a Mac) connector to use this.

2) For the extra $80 go with the 6GB. Even assuming you can compress the 7TB down to 4TB, you don't actually get 4TB out of this once it's formatted. Parity data will take up further room and if you have extra space you can use it for incremental (daily) backups.

3) Make sure you have real backup software. My experience is that the stuff that ships with Windows & these hardware are functional but not optimal and tend not to work with OS upgrades 100% of the time. This may have changed, but good software is a time saver .. especially when your looking for that one file in a Zip file from months ago.

4) Make sure this will fit, securely and dry, in where you plan on storing it offsite. One client bought a similar set-up to store his office's BUs in his safe at home .. problem is that the safe was just too small (by a inch or so) due to the shelves built into the safe  

Last place I worked at had an external LTO-5 Tape system. Initial cost is much higher but long term costs (if you plan on doing daily or weekly backups with lots of data) is less. Of course there are issues with tape as well (software, cartridge availability & speed to name a few).

Good luck