A new generation of gaming consoles is due to hit the market later this year, and the hype cycle for the Xbox Series X and Playstation 5 has been underway for more than a year. Solid technical details (as opposed to mere rumors) have been slower to arrive, and we still know much less about the consoles than we typically know about PC platforms and components during the post-announcement, pre-availability phase. We have some top-line performance numbers and general architectural information from Microsoft and Sony, but not quite a full spec sheet.

The new generation of consoles will bring big increases in CPU and GPU capabilities, but we get that with every new generation and it's no surprise when console chips get the same microarchitecture updates as the AMD CPUs and GPUs they're derived from. What's more special with this generation is the change to storage: the consoles are following in the footsteps of the PC market by switching from mechanical hard drives to solid state storage, but also going a step beyond the PC market to get the most benefit out of solid state storage.


Xbox Series X internals

Solid State Drives were revolutionary for the PC market, providing immense improvements to overall system responsiveness. Games benefited mostly in the form of faster installation and level load times, but fast storage also helped reduce stalls and stuttering when a game needs to load data on the fly. In recent years, NVMe SSDs have provided speeds that are on paper several times faster than what is possible with SATA SSDs, but for gamers the benefits have been muted at best. Conventional wisdom holds that there are two main causes to suspect for this disappointment: First, almost all games and game engines are still designed to be playable off hard drives because current consoles and many low-end PCs lack SSDs. Game programmers cannot take full advantage of NVMe SSD performance without making their games unplayably slow on hard drives. Second, SATA SSDs are already fast enough to shift the bottleneck elsewhere in the system, often in the form of data decompression. Something aside from the SSD needs to be sped up before games can properly benefit from NVMe performance.

Microsoft and Sony are addressing both of those issues with their upcoming consoles. Game developers will soon be free to assume that users will have fast storage, both on consoles and on PCs. In addition, the new generation of consoles will add extra hardware features to address bottlenecks that would be present if they were merely mid-range gaming PCs equipped with cutting-edge SSDs. However, we're still dealing with powerful hype operations promoting these upcoming devices. Both companies are guilty of exaggerating or oversimplifying in their attempts to extol the new capabilities of their next consoles, especially with regards to the new SSDs. And since these consoles are still closed platforms that aren't even on the market yet, some of the most interesting technical details are still being kept secret.

The main source of official technical information about the PS5 (and especially its SSD) is lead designer Mark Cerny. In March, he gave an hour-long technical presentation about the PS5 and spent over a third of it focusing on storage. Less officially, Sony has filed several patents that apparently pertain to the PS5, including one that lines up well with what's been confirmed about the PS5's storage technology. That patent discloses numerous ideas Sony explored in the development of the PS5, and many of them are likely implemented in the final design.

Microsoft has taken the approach of more or less dribbling out technical details through sporadic blog posts and interviews, especially with DigitalFoundry (who also have good coverage of the PS5). They've introduced brand names for many of their storage-related technologies (eg. "Xbox Velocity Architecture"), but in too many cases we don't really know anything about a feature other than its name.

Aside from official sources, we also have leaks, comments and rumors of varying quality, from partners and other industry sources. These have definitely helped fuel the hype, but with regards to the console SSDs in particular, these non-official sources have produced very little in the way of real technical details. That leaves us with a lot of gaps that require analysis of what's possible and probable for the upcoming consoles to include.

What do we know about the console SSDs?

Microsoft and Sony are each using custom NVMe SSDs for their consoles, albeit with different definitions of "custom". Sony's solution aims for more than twice the performance of Microsoft's solution and is definitely more costly even though it will have the lower capacity. Broadly speaking, Sony's SSD will offer similar performance to the high-end PCIe 4.0 NVMe SSDs we expect to see on the retail market by the end of the year, while Microsoft's SSD is more comparable to entry-level NVMe drives. Both are a huge step forward from mechanical hard drives or even SATA SSDs.

Console SSD Confirmed Specifications
  Microsoft
Xbox Series X
Sony
Playstation 5
Capacity 1 TB 825 GB
Speed (Sequential Read) 2.4 GB/s 5.5 GB/s
Host Interface NVMe PCIe 4.0 x4 NVMe
NAND Channels   12
Power 3.8 W  

The most important and impressive performance metric for the console SSDs is their sequential read speed. SSD write speed is almost completely irrelevant to video game performance, and even when games perform random reads it will usually be for larger chunks of data than the 4kB blocks that SSD random IO performance ratings are normally based upon. Microsoft's 2.4GB/s read speed is 10–20 times faster than what a mechanical hard drive can deliver, but falls well short of the current standards for high-end consumer SSDs which can saturate a PCIe 3.0 x4 interface with at least 3.5GB/s read speeds. Sony's 5.5GB/s read speed is slightly faster than currently-available PCIe 4.0 SSDs based on the Phison E16 controller, but everyone competing in the high-end consumer SSD market has more advanced solutions on the way. By the time it ships, the PS5 SSD's read performance will be unremarkable – matched by other high-end SSDs – except in the context of consoles and low-cost gaming PCs that usually don't have room in the budget for high-end storage.

Sony has disclosed that their SSD uses a custom controller with a 12-channel interface to the NAND flash memory. This seems to be the most important way in which their design differs from typical consumer SSDs. High-end consumer SSDs generally use 8-channel controllers and low-end drives often use 4 channels. Higher channel counts are more common for server SSDs, especially those that need to support extreme capacities; 16-channel controllers are common and 12 or 18 channel designs are not unheard of. Sony's use of a higher channel count than any recent consumer SSD means their SSD controller will be uncommonly large and expensive, but on the other hand they don't need as much performance from each channel in order to reach their 5.5GB/s goal. They could use any 64-layer or newer TLC NAND and have adequate performance, while consumer SSDs hoping to offer this level of performance or more with 8-channel controllers need to be paired with newer, faster NAND flash.

The 12-channel controller also leads to unusual total capacities. A console SSD doesn't need any more overprovisioning than typical consumer SSDs, so 50% more channels should translate to about 50% more usable capacity. The PS5 will ship with "825 GB" of SSD space, which means we should see each of the 12 channels equipped with 64GiB of raw NAND, organized as either one 512Gbit (64GB) die or two 256Gbit (32GB) dies per channel. That means the nominal raw capacity of the NAND is 768GiB or about 824.6 (decimal) GB. The usable capacity after accounting for the requisite spare area reserved by the drive is probably going to be more in line with what would be branded as 750 GB by a drive manufacturer, so Sony's 825GB is overstating things by about 10% more than normal for the storage industry. It's something that may make a few lawyers salivate.

It's probably worth mentioning here that it is unrealistic for Sony to have designed their own high-performance NVMe SSD controller, just like they can't do a CPU or GPU design on their own. Sony had to partner with an existing SSD controller vendor and commission a custom controller, probably assembled largely from pre-existing and proven IP, but we don't know who that partner is.

Microsoft's SSD won't be pushing performance at all beyond normal new PC levels now that OEMs have moved beyond SATA SSDs, but a full 1TB in a PC priced similarly to consoles would still be a big win for consumers. Multiple sources indicate that Microsoft is using an off-the-shelf SSD controller from one of the usual suspects (probably the Phison E19T controller), and the drive itself is built by a major SSD OEM. However, they can still lay claim to using a custom form factor and probably custom firmware.

Neither console vendor has shared official information about the internals of their SSD aside from Sony's 12-channel specification, but the capacities and performance numbers give us a clue about what to expect. Sony's pretty much committed to using TLC NAND, but Microsoft's lower performance target is down in the territory where QLC NAND is an option: 2.4GB/s is a bit more than we see from current 4-channel QLC drives like the Intel 665p (about 2GB/s) but much less than 8-channel QLC drives like the Sabrent Rocket Q (rated 3.2GB/s for the 1TB model). The best fit for Microsoft's expected performance among current SSD designs would be a 4-channel drive with TLC NAND, but newer 4-channel controllers like the Phison E19T should be able to hit those speeds with the right QLC NAND. Either console could conceivably in the future get a double-capacity version that uses QLC NAND to reach the same read performance of the original models.

DRAMless, but that's OK?

Without performance specs for writes or random reads, we cannot rule out the possibility of either console SSD using a DRAMless controller. Including a full-sized DRAM cache for the flash translation layer (FTL) tables on a SSD primarily helps performance in two ways: better sustained write speeds when the drive's full enough to require a lot of background work shuffling data around, and better random access speed when reading data across the full range of the drive. Neither of those really fits the console use case: very heavily read-oriented, and only accessing one game's dataset at a time. Even if game install sizes end up being in the 100-200GB range, at any given moment the amount of data used by a game won't be more than low tens of GB, and that is easily handled by DRAMless SSDs with a decent amount of SRAM on the controller itself. Going DRAMless seems very likely for Microsoft's SSD, and while it would be very strange in any other context to see a 12-channel DRAMless controller, that option does seem to be viable for Sony (and would offset the cost of the high channel count).

The Sony patent mentioned earlier goes in depth on how to make a DRAMless controller even more suitable for console use cases. Rather than caching a portion of the FTL's logical-to-physical address mapping table in on-controller SRAM, Sony proposes making the table itself small enough to fit in a small SRAM buffer. Mainstream SSDs have a ratio of 1 GB of DRAM for each 1 TB of flash memory. That ratio is a direct consequence of the FTL managing flash in 4kB chunks. Having the FTL manage flash in larger chunks directly reduces the memory requirements for the mapping table. The downside is that small writes will cause much more write amplification and be much slower. Western Digital sells a specialized enterprise SSD that uses 32kB chunks for its FTL rather than 4kB, and as a result it only needs an eighth the amount of DRAM. That drive's random write performance is poor, but the read performance is still competitive. Sony's patent proposes going way beyond 32kB chunks to using 128MB chunks for the FTL, shrinking the mapping table to mere kilobytes. That requires the host system to be very careful about when and where it writes data, but the read performance that gaming relies upon is not compromised.

In short, while the Sony SSD should be very fast for its intended purpose, I'm going to wager that you really wouldn't want it in your Windows PC. The same is probably true to some extent of Microsoft's SSD, depending on their firmware tuning decisions.

Expandability

Both Microsoft and Sony are providing expandability for the NVMe storage of their upcoming consoles. Microsoft's solution is to re-package their internal SSD into a custom removable form factor reminiscent of what consoles used back when memory cards were measured in MB instead of TB and before USB flash drives were ubiquitous. Since it uses all the same components, this expansion card will be functionally identical to the internal storage. The downside is that Microsoft will control the supply and probably pricing of the cards; currently Seagate is the only confirmed partner for selling these proprietary expansion cards.

Sony is taking the opposite approach, by giving users access to a standard M.2 PCIe 4.0 slot that can accept aftermarket upgrades. The requirements aren't entirely clear: Sony will be doing compatibility testing with third-party drives in order to publish a compatibility list, but they haven't said whether drives not on their approved list will be rejected by the PS5 console. To make it onto Sony's compatibility list, a drive will need to mechanically fit (ie. no excessively large heatsink) and offer at least as much performance as Sony's custom internal SSD. The performance requirements mean no drive currently available at retail will qualify, but the situation will be very different next year.

Balancing the System: Other Hardware Features
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  • JStacts - Tuesday, June 30, 2020 - link

    "The problem is that upgrading is a necessity." Upgrading a computer is no more necessary that buying a new console (I would argue less). The difference is that the PC game can upgrade when he wants and is not forced into a cycle by a multi-national corporation. I built my computer a few years ago with an RX480. Could I upgrade? Sure. I could have upgraded last year, or the year before. I could upgrade next year.

    It is entirely my choice when or even if I upgrade. It is my choice how much to spend on the upgrade. It is my choice because of the incredible wealth of options offered by the PC market.

    If I had a PS4, I had to wait until Sony CHOSE to release the Pro version (which they had no obligation to do) or the PS5.

    Next year, I will very probably buy a couple monitors and upgrade my GPU, but I certainly don't feel compelled to do so. I enjoy my gaming experience.

    It is this difference of choice that makes my say that "I get to upgrade" instead of "I have to upgrade".

    You mentioned that we (PC gamers) spend thousands to keep up with the state of software. While there certainly are those people (and you will meet a disproportionate number of them in the AT comment section), I would hardly call that a fair generalization of the PC gaming community. Most of us keep our components for many years before upgrading. Most of us are perfectly happy buying low or midrage parts and the gaming experiences those offer. A significant portion of us use very low end hardware.

    If you're not already acquainted with the channel, I recommend "The LowSpec Gamer" on Youtube. His entire channel is dedicated to making AAA games run on extremely low-end hardware.
    Reply
  • Oxford Guy - Monday, June 15, 2020 - link

    "What makes a console a good piece of hardware is that I do not have to even care what is inside the box that runs the games since the games that I buy for said console will just work as intended. Every generation has extensive discussion about hardware and the usual comparing and penis measuring between brands. It all ends up being meaningless when you pick up a controller and play a game on it which is far and above the hassle of PC gaming in terms of equipment apathy. In short, IDGAF what drive is inside the thing. Insert disc (or download digital copy) and game on!"

    Thank you MS or Sony employee for this attempt to justify the "console" scam.
    Reply
  • zmatt - Tuesday, June 16, 2020 - link

    Adding internal storage and internet connectivity destroyed what I saw as the two big advantages with consoles. It used to be that you didn't have to install anything and you didn't have to patch anything. Developers were forced to released games as complete and working products and playing them was truly as simple as sticking a disc in and playing.

    Sure load times and graphics suffered because of it but consoles shouldn't try to compete with PCs on performance anyways. Its a fool's errand. Back then you could truly say consoles just worked. Having to wait for games to install, having to manage updates and dealing with buggy releases were largely problems that PC users had to put up with.

    Now consoles have all of those problems too. You can't seem to power on a console today without first waiting for it to update before letting you do anything. And unlike on a PC where you have control of such things the console will force you to update both it and the games before letting you play them. The only way around it is to disconnect networking entirely which renders half of its functionality broken.

    If I can't just slap in a disc and play then why bother? If I have to expend effort then I might as well get the full benefit of a PC. Not this halfway point consoles have reached.
    Reply
  • PeachNCream - Tuesday, June 16, 2020 - link

    I think its actually a good thing that consoles have access to internet-based patching and multiplayer capabilities as well. There is a lot more code in a modern game than was the case with cartridge-based systems and early even the first couple of generations of disc-based consoles. Deploying an update is a reality of modern software we just have to cope with and work around these days regardless of the platform.

    In addition, if you keep an eye on the ROM hacking and modding community, you will see there are still hobbyists out there finding and fixing bugs that are present in 8- and 16-bit era cartridge based games that have a total memory footprint of a few hundred kilobytes to a single digit number of megabytes due to technology and cost limits of the time period. (Lots of Final Fantasy 3/6 fixes for the SNES for example).
    Reply
  • ToTTenTranz - Friday, June 12, 2020 - link

    Small correction at the end of page 1:

    Cerny said the 3rd party SSDs will need to be faster than the PS5's rated 5.5GB/s, because consumer SSDs only have 2 priority lanes, whereas the PS5's has 6 lanes.
    So the extra speed is needed to compensate for a less effective system of I/O interrupts. A 3rd party 5.5GB/s SSD is supposedly not capable enough to put in the PS5 as extra storage.
    Reply
  • close - Friday, June 12, 2020 - link

    I wonder if there will be a market for after market SSDs that do match (or get sufficiently close to) the performance of the built in one. Also if MS plans on introducing a higher performance builtin SSD in future model refreshes. Reply
  • ToTTenTranz - Friday, June 12, 2020 - link

    Even if Microsoft does introduce a higher performance SSD in later models, the baseline is set in stone with this 2.4GB/s + BCPack & Zlib architecture. Reply
  • brucethemoose - Friday, June 12, 2020 - link

    They could easily do another mid gen update with a faster SSD. Reply
  • surt - Friday, June 12, 2020 - link

    They could, but the point is that developers can't rely on it. Reply
  • Tams80 - Friday, June 12, 2020 - link

    The whole point of a new 'generation' is that the baseline is reset. Consumers (partly for their own good) are expected to buy a new console, so developers will know that that one will be what millions of people will have.

    Mid-life upgrades work to an extent, but limiting games to just the newer models while the old models are still 'current' greatly reduces the potential market. They do work for making existing features better, but new or different features just aren't going to be worth investing in for most developers.
    Reply

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