[grepfru_it]

LTO. I bought an LTO-5 system to backup 6TB of critical data and 12TB of nice-to-have data. LTO-6 is better if you can afford it.

Downside to tape backup is you need throughput, or the ability to do disk-disk backups

[dist-epoch]

For 20 TB LTO seems too expensive.

20 TB of SSD costs about $1000.

Or you could get a 20 TB hard drive for $300.

[grepfru_it]

Drive failure and managing those drives are hidden costs you are not considering.

I have had multiple hard drives fail and been left stranded. Tape fails but not nearly as often as disks

LTO6 and LTO7 are not expensive for 20TB