Is it a new, unused drive? I had similar problems when testing disks that came back from customers. What size is diplayed in the SSA? (Smart Storage Administrator) Does the RAID controller recognise the disk correctly? Have you configured a single disk RAID 0+1?
If the RAID is configured properly, then run DISKPART from the command line. Enter list disk. Choose your 3TB drive with "select disk 1 (or 2 or 3 or....)" and the type "clean". Just make sure you selected the right disk or your date will be gone!
Is the disk size correct now?
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"If it seems illogical... you just don't have enough information"
