(All thanks to this guy: https://www.reddit.com/r/PS3/duplicates/qlf8mk/2tb_ssd_on_ps3_works_as_1525_gb/)
By default, PS3 doesn't support 2TB drives.
If you have a 2TB storage (HDD/cheap SSD) you want to use with a PS3, you can 'convert' it to 1.5TB which will work without problems with a PS3...