ReadyNAS or Synology for me?

I started in 2007 with an Infrant (Netgear bought them out) NV+ and two 500GB hard drives. Over the next three years, I expanded it to 4x500GB drives. I then added an NVX with 4x1TB drives and upgraded the NV+ to the same configuration. It was at this point, that I discovered the security of rsync where one ReadyNAS synchronizes the file to a second ReadyNAS. This process permits me to have the security of knowing that every night starting at midnight my primary NAS would be backed up without my involvement. The process usually only take minutes as it only updates the changed portion of files, added files and deleted files.

We always seem to underestimate how our collections will grow. When I started with a total 500GB volume it seemed like that would last forever, as I only had about 61GB of pictures and financial files, with a few video clips. Over the years, as I added more and more video clips, I had to add a third 500GB drive and then a fourth. At this point I had about 500GB of data, so when I went to the NVX with a 2.7TB volume, I thought that would last for a long time. It did - one year before I replaced two TB drives with two 3TB drives and I now have 1.8TB of data on a 4.5TB volume.

Figure out what volume you think you will need and then triple it. The Ultra 2 can currently support a redundant volume of 3TB (2.7TB after overhead) while the Ultra 4 will currently support a redundant volume of 9TB (8.1TB after overhead). Right now, you don't download or copy very many video files because of the disk volume they take. Once you add a large centralized storage device, you will start adding to it.

I know the Ultra 4 was not on your original list, but consider starting with it and 2x2TB drives. Another feature of a single X-Raid2 volume is that you don't have arbitrary limits set on any type of files. If you run low on space, you can expand, either by adding drives, or increasing the size of the drives.