Nobody builds a 4tb 2.5" harddrive, so 3tb is gonna be the biggest HDD. Technically you could probably use an enterprise grade SSD somewhere in the 8tb range - I'm not really sure at what point they start getting thicker than 9.5mm though. Course those cost more than a typical used car anyway, so probably a moot point.
PS3's can only handle 1TB because of the way they handle partitions. Massive oversight on Sony's part, tbh
And here was me giving them the benefit of the doubt of having implemented basic protocol competently.
Remember when the ps3 first came out and everyone was like "HOLY *Can'tSayThisOnTV*, WHO IS EVER GOING TO NEED A 80gb DRIVE IN THEIR GAME CONSOLE"?
Sony used Fat-32 for the PS3's drive, Which only supports partitions up to 2TB. FAT was the de-facto standard for embedded devices and things like consoles back in 2006ish, which makes it a reasonable choice. The idea was the even though the possibility of n-TB drives was looming, the other hardware would be a bottleneck long before the hard drive became an issue, which largely, it has. There's a chance that the PS3 MAY be able to handle a 2TB drive connected with a cable on newer firmwares, but in my experience the PS3 will just read a 2TB drive as 1TB, and won't let the console touch the other half of the drive. This might be because of the hypervisor, or some sort of security thing on Sony's part.
