Only just now ordered a trio of 10 TB WD Red Plus drives, so will either do a Mirror plus one more copy (totaling 20 TB w/ 3 drives), or perhaps a striped array through Storage Spaces as long as adjust the cluster size from 4k up to something higher than the classic striped array Storage Spaces throughput of a staggering 32 MB/sec...!
(If unsuccessful in getting stripe speeds up to something semi-normal for a trio of striped drives, realizing that writes will take a hit over reads of course due to parity, then I'll revert to just a mirror, with an additional copy, which oddly enough can also be done in Storage Spaces as well with adding another drive to a mirror, where apparently SS simply staggers it's 2 copies of files semi-evenly to balance the storage amongst the 3 drives. Will tinker with read/write results from/to un-cached file transfers to see which is best.
(The article was correct, the price on 20 TB Pro X300 looked nice! Might pick one of those up too, but, I expect the trio of 30 TB raw to last me a while, considering how long a smattering of external USB-connected drives have lasted, with the largest being a 3 TB Toshiba, and it being only some 30% full! I have anything truly important also backed up to multiple free cloud accounts.)
Sidenote: any else trying TerraBox? Free 1 TB? Seems to work fine the 3 weeks I have been tinkering with it! 1 TB for free users sure beats most classic/well established competitors with their paltry 5, 10, 30 GB free storage limits, etc...)