Synology / DSM 20TB support?

[Enquiries]

My latest Bluray rips are now 50GB+ w/4K and DTS/HD each, so my needs have increased. Currently my "MediaStorm" is 30TB. Just purchased a Syn1621+ w/20TB Seagate IronWolf Pro, 32G RAM w/2TBx2 NVME. SYN/DSM only recognizes a little under 90T, assuming this is bc the 20's are not yet verified>? I would expect a single disk loss w/RAID5, yielding 5x20T or 100T of usable capacity, I get ~87TB, is this due to DSM? I like the Synology HW, so can i remove DSM and just use FreeNAS or other to get back my 10+ TB? Prior to building my storage pools, docker apps etc, I need to have a good start, and losing 10+ TB from the start doesn't seem right. When will 20TB disks be valid/ verified? There are less than a handful out there, so I can't imagine the SYN team is that busy testing new storage gear, esp if the unit is a "storage" unit, and not just a multi-core server to stack apps on. Looking or a higher yield on my 6x20 base, what to do?";}

[ed]

Yes, with 5x20TB drives in RAID5 (SHR1) you will get around 75TB of usable storage space.
Each 20TB drive actually have only 18.19TB of actual storage space available. More info here https://platinumdatarecovery.com/hard-dr...calculator
And RAID5/SHR1 will allocate one of those drives for redundancy. More info here http://www.raid-calculator.com/default.aspx
Synology will not cap the available storage space on 20TB drives even though they have not tested them yet.

I hope this helps.