Solution: There never was a second drive. It must have been a partition that got wiped with the install, but there’s only the NVME in there. Sorry, guys. I dig around in my innards very frequently and just thought I was mounting a second drive this entire time. Hooray for backups.
reinstalled Mint and my second drive is absolutely invisible to everything. I can’t mount what I can’t see. I’m thinking of unplugging it and plugging it back in just because I’m out of ideas.
What could have caused a drive to become invisible after a reinstall?
Edit: Checked bios. All security disabled. Using AHCI and UEFI (tried CSM). I don’t really know what these things mean, I just know things were working properly before I reinstalled mint so I’m puzzled why it could be a BIOS issue.
Current lsblk:
<pre>NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sr0 11:0 1 1024M 0 rom
nvme0n1 259:0 0 953.9G 0 disk
├─nvme0n1p1 259:1 0 1M 0 part
├─nvme0n1p2 259:2 0 513M 0 part /boot/efi
└─nvme0n1p3 259:3 0 953.4G 0 part / </pre>


Check cables. Verify whether or not it’s even spinning up. Try a different sata port. Try a different power plug. Try the drive in another machine.
Yes, thank you for this, motivated me to pull the drive only to find out to my confusion that it wasn’t there… mostly likely I was mounting a partition this entire time. Good news is that I have n 8-year-old 4TB and and 12-year-old 3TB I might as well consume.