ReRAM is a type of non-volatile RAM that has tremendous advantages over NAND memory like consuming less power, scalability into smaller form factors past 15nm, can be stacked with 3D cross-point arrays (hence Intel's XPoint memory), and it's also far more durable than flash memory.
Unlike DRAM, which stores a charge, ReRAM creates resistance by passing an electric current through two types of materials, which is then read as a 1 or a 0.
Sony has been working on its own ReRAM solutions since 2013, when it teamed up with Micron to start developing 16Gb chips, and now expects to start shipping ReRAM solutions in 2020 for the enterprise market.
We could see Sony's ReRAM modules being used or adapted in the PS5 to accelerate speeds dramatically.
ReRAM would essentially work like an Optane module, storing the most-used files and data blocks on its built-in cross-point RRAM memory cells as cached data, and then beaming them directly to other system components like the GPU and CPU for processing.
The idea is that Sony would pair its ReRAM modules up with an SSD to accelerate overall data loading by means of super-fast caching.
ReRAM wouldn't need to replace the PlayStation 5's SSD but work alongside it. This way, Sony could use cheaper 2TB NVMe PCIe 3.0 drives or even SATA drives to ensure the PS5's purported $499 MSRP.
Sony could theoretically make an entire SSD drive out of ReRAM for the PlayStation 5, but that'd be quite costly and might produce some serious heat. It's pretty unlikely to see a whole ReRAM SSD just for the PlayStation 5. If anything, we'll probably see a separate smaller module fastened to the PS5's motherboard that boosts SSD speeds, as we outlined above.
Sony recently outlined some details on its ReRAM in a big presentation at the Persistent Memory Summit 2019 show.
Sony is targeting 128GB and 256GB capacities for its ReRAM SSDs. Remember, these are fully-fledged SSDs, not a smaller module. These capacities could be overkill for the PlayStation 5 both in price and performance, and we should see smaller chips being made special for the console.
Using PCIe 5.0 on x16 lanes, Sony's ReRAM SSD drives are expected to hit the following speeds:
- 128GB (8x 128Gb) - 25.6GB/s read, 9.6GB/s write
- 256GB (16x 128Gb) - 51.2GB/s read, 19.2GB/s write
Again, the PlayStation 5 won't hit theses speeds. These are higher-end ReRAM-enabled SSDs made specifically for the enterprise market.
There are some concerns, though. Right now, ReRAM can require more power than DRAM (at least in these higher capacities), and Sony says they have to be cautious to the memory controller while designing ReRAM solutions for small-form-factor systems, which likely include the PS5.
This kind of solution would enable fast game startups, quick data loading, and it would also speed up data rates on older mechanical HDDs or SSDs--which is perfect for anyone who holds most of their console games on an external drive.
"The raw read speed is important, but so are the details of the I/O mechanisms and the software stack that we put on top of them. If I got a PlayStation 4 Pro and then I put in a SSD that cost as much as the PlayStation 4 Pro-it might be one-third faster," Sony's Mark Cerny said in an interview with Wired.
Speed isn't everything, though. PlayStation 5 architect Mark Cerny confirms the new ultra-fast SSD will come with customized software on the OS level that allows for hybrid data installs. This means gamers could theoretically choose what portions of a game they want to install, dramatically reducing install sizes.
The PlayStation 5 will support massive 100GB BD-XL Blu-ray discs, which is great because games are getting monstrous. Thankfully we can carve up the choice bits and only install, say, multiplayer, or the campaign of a game.
"Rather than treating games like a big block of data, We're allowing finer-grained access to the data," Cerny told Wired.
Tightening up shared hardware synergy with cache acceleration
The potential here is tremendous, especially for a closed ecosystem like a console with unified system components and a customized OS.
Consoles typically share RAM and VRAM in the same memory pool accessed by the onboard APU, and in this case, both PlayStation 5 and Project Scarlett will use a Zen 2 CPU and Navi GPU on the same SoC with built-in GDDR6 system memory.
Unified by Optane-like or ReRAM cache acceleration tech, the storage drives will join the CPU, GPU, and DRAM pool (in this case, VRAM and DRAM are shared) to directly feed the components with important data.
Both the GPU and CPU would benefit from quicker data access, allowing for the PS5's insane 0.8 second loading times in Spider-Man as well as speedy access to game textures, environment assets, and rendering effects. Texture pop-in might be a thing of the past, thanks to this storage tech.
Speaking of system memory, the cache tech can also recruit RAM to supercharge data speeds even more. Apparently, Microsoft has taken this a step even further.
They recently confirmed they're using Project Scarlett's SSD as a VRAM buffer, which is something that Optane and ReRAM modules can apparently do. Optane can't really replace RAM, but it can complement existing system RAM to boost performance. Since DRAM and VRAM is shared in the console environment, this seems entirely within the realm of possibility for cache-accelerated next-gen console storage.
"We've created a new generation of SSD. We're actually using the SSD as virtual RAM. We're seeing more than 40x performance increases over the current generation," Microsoft said in the Project Scarlett E3 2019 reveal video.
"The combination of the SoC and the solid state drive are really what gives you a totally new experience.""Now we can take all of that power and apply all of that back into the scene, and generate more life into that world and bring it to the gamer in a seamless way."
There's another possibility: Both the PlayStation 5 and Project Scarlett could use tiered storage, which would allow lower-cost, high-capacity HDDs and high-speed SSD combos in the systems.