PS5 owners will be able to add more storage space using an external hard drive or by installing an M2 SSD in a dedicated expansion port, system architect Mark Cerny announced on today's reveal stream.
PS5 will support USB external hard drives, but it will only be able to use these drives to play PS4 games through backwards compatibility. You'll also be able to copy PS4 games directly to the PS5's built-in SSD to improve loading times. However, if you want more space to play PS5 games, you'll need another SSD. For comparison, the Xbox Series X storage can be expanded using proprietary memory card-esque SSD chips.
"We will be supporting certain M2 SSDs," Cerny confirmed. "These are internal drives that you can get on the open market and install in a bay on the PS5. They connect through the custom IO unit just like our SSD does, so they can take full advantage of the decompression, IO co-processors, and all the other features I was talking about. Here's the catch though: that commercial drive has to be at least as fast as ours. Games that rely on the speed of our SSD need to work flawlessly with any M2 drive."
The stock PS5 SSD reads at 5.5GB/s, while most PCIe 3.0 M2 SSDs on the market today hover between 3GB/s and 4GB/s. However, Cerny and Sony expect PCIe 4.0 SSDs capable of speeds of up to 7GB/s to be readily available by the end of the year. These are the kinds of drives PS5 owners will need to purchase if they want to expand their SSD storage, but only specific drives will work. Additional drives need to fit the PS5's installation bay, for one, and the internals also need to be compatible.
"Right now, we're getting M2 drive samples and benchmarking them in various ways," Cerny explains. "When games hit beta as they get ready for the PS5 launch at year end, we'll also be doing some compatibility testing to make sure that the architecture of particular M2 drives isn't too foreign for the games to handle. Once we've done that compatibility testing, we should be able to start letting you know what drives will physically fit and which drive samples benchmark appropriately high in our testing. It would be great if that happened by launch, but it's likely to be a bit past it, so please hold off on getting that M2 drive until you hear from us."
In other words, assuming capable PCIe 4.0 M2 SSDs are indeed available when PS5 launches, you won't really be able to choose one until Sony releases the compatibility requirements, likely in early 2021 at best. Expect to see Sony launch or brand an official line of PS5 expansion SSDs around this time. The good news is that even the most avid players shouldn't burn through the drive's default storage in that time.
Sony reckons "SSD is key" for next-gen games and hardware.