[SOLVED] Low SSD tetrabytes when in Raid 0

[pawinda]

I have had an AKiTiO Thunder3 Duo Pro enclosure since March 2017. It has physical settings of SPAN, JBOD, Raid 0, and Raid 1. I always set it to Raid 0. Initially, I installed two (2) Samsung 860 EVO 2TB drives and, after initializing via Control Panel>Admin Tools>Disk Management, I had 3.73 usable TB. I later replaced the EVO's with two (2) Samsung 870 QVO 4TB drives in Raid 0 and had 7.63TB usable space. I just upgraded to two (2) Samsung 870 QVO 8TB (still in hardware Raid 0) but only have 14.5TB usable space. This seems very low even with any overhead used. (I also have a PCIE HighPoint 7101A with four (4) XPG SX8200 Pro 2TB NVME SSD's installed in SOFTWARE Raid 0 and have 7.45 usable space). Any input on why my present TB space is 1.5TB below the 16TB the QVO drives should provide would be greatly appreciated.

 

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[USAFRet]

I have had an AKiTiO Thunder3 Duo Pro enclosure since March 2017. It has physical settings of SPAN, JBOD, Raid 0, and Raid 1. I always set it to Raid 0. Initially, I installed two (2) Samsung 860 EVO 2TB drives and, after initializing via Control Panel>Admin Tools>Disk Management, I had 3.73 usable TB. I later replaced the EVO's with two (2) Samsung 870 QVO 4TB drives in Raid 0 and had 7.63TB usable space. I just upgraded to two (2) Samsung 870 QVO 8TB (still in hardware Raid 0) but only have 14.5TB usable space. This seems very low even with any overhead used. (I also have a PCIE HighPoint 7101A with four (4) XPG SX8200 Pro 2TB NVME SSD's installed in SOFTWARE Raid 0 and have 7.45 usable space). Any input on why my present TB space is 1.5TB below the 16TB the QVO drives should provide would be greatly appreciated.

There is nothing wrong, you've not lost any space.
It's not "overhead", or formatting, or anything to do with RAID.
This is simply a difference in reporting units.

Base 10 vs Base 2
Human vs Computer

It is this way for all storage devices.
A "1TB" drive will read as 931GB in Windows.
2TB as 1.81TB.

Extrapolate up for your 16TB, and you'll see exactly what you see.