Comment Re:My 2 cents (Score 1) 609
The theoretical limit of a DS1010+ and a DX510 (which is the only Synology offering in the 20 TB range) is actually 16 TB due to them using ext3. With 2 TB drives the best you can actually get are 14.5 TB with RAID-6 or RAID-5+Hotspare. Spanning a RAID-5 over all disks would result in a volume slightly larger than 16 TB, which will not work. I've tried it.
Still, 14.5 TB is pretty much okay in my book. If you actually do need more, build a Backblaze pod (same price league as two DS1010+ with a DX510 ea.; more then double the drives of that) or be spendy and get an X4500 (related as far as the number of drives goes. A completely different class in all other aspects.)