Storage matters: why SSDs in Xbox and Playstation herald a new era in console gaming





A new generation of game consoles is coming out this year, and the hype associated with the Xbox Series X and Playstation 5 has not ceased for more than a year. Real technical details, not just rumors, leaked out slowly, and today we still know too little about these consoles compared to how much we usually know about future PC platforms after their announcement, even before they go on sale. . We have some figures from Microsoft and Sony related to maximum performance, but not a complete list of specifications.



The new generation of consoles will become more powerful in both CPU and GPU, but this is true for each new generation, and it comes as no surprise when console chips update the microarchitecture in the same way as the CPU and GPU from AMD, from which they originate. More interesting is the change in storage layout for the new consoles - they are not just following the PC market and moving from mechanical hard drives to solid state drives, they are surpassing it, aiming to get the most out of the use of solid state drives.





Inside Xbox Series X



SSDs revolutionized the PC market with incredible performance improvements. Games benefited mainly from faster installs and faster downloads, but the faster storage also helps reduce latency and eliminate jitter when the game loads data on the fly. In recent years, NVMe solid state drivesspeeds on paper were several times higher than in principle possible for solid-state drives on the SATA interface, but for the players the advantages of the former were rather blurred. Common sense says that two factors are to blame for this frustration: First, almost all games and game engines are still designed to be played from a hard drive, since existing consoles and less advanced PCs do not have solid state drives. Game programmers cannot take full advantage of NVMe without making their games completely unplayable when they use a hard drive. Secondly, SATA SSDs have already become fast enough to transfer the title of a bottleneck to some other part of the system, for example, to the process of unpacking data. Need to speed up something elsein addition to solid state drives, in order for games to begin to receive all the advantages of NVMe performance.



Microsoft and Sony are working on both of these issues in their new consoles. Soon, game developers can safely assume that users will have very fast storage devices, both on consoles and PCs. In addition, the new generation of consoles will add additional hardware designed to eliminate the bottlenecks they would have if it were just a mid-range PC with a very fast solid state drive. However, so far we have only powerful hype that advertises future devices. Both companies are seen in exaggerating or oversimplifying the situation when they try to embellish the new features of their future consoles - especially in terms of solid state drives. And since these consoles are still closed platforms that have not appeared on the market,some of the more interesting technical details are still kept secret.







The main source of official technical information about the PS5 (and in particular its solid state drive) is the lead designer Mark Cerny. In March, he gave an hour-long talk on the technical side of the PS5, and devoted about a third of the time to drives. Less official sources include Sony patent applications that appear to be related to the PS5 - including one that goes well with the confirmed details about the storage technology on that console. The patent reveals many of the ideas the company explored during the development of the PS5, and many of them will surely end up in the final product.



Microsoft decided to leak technical details in a thin stream, scattering information on periodic blog posts and interviews, especially with the DigitalFoundry website (which also described PS5 well). There, the company revealed the registered names of many technologies related to storage devices (for example, Xbox Velocity Architecture), but in many cases, apart from the name of the technology, we do not know anything more about it.



In addition to official sources, we have leaks, comments, and rumors of varying quality from partners and other sources in the industry. They definitely help keep the hype, but specifically about the use of solid state drives in consoles, these rumors provide very little technical details. We still have a lot of gaps requiring an analysis of what is possible and what is likely to be in the new consoles.



What do we know about these consoles' SSDs?



Microsoft and Sony use special solid state drives such as NVMe, although they are "special" in different ways. Sony's solution is trying to double the speed of Microsoft's solution, and it will definitely be more expensive, albeit less bulky. Overall, the performance of Sony SSDs should be comparable to the most expensive PCIe 4.0 NVMe SSDs due out in retail at the end of the year, while Microsoft SSDs are better compared to entry-level NVMe drives. However, both options are a big step up from mechanical hard drives and even SATA SSDs.



Solid State Drives Confirmed Specifications

Microsoft Xbox Series X Sony Playstation 5
Volume 1 TB 825 GB
Sequential read speed 2.4 GB / s 5.5 GB / s
Interface NVMe PCIe 4.0 x4 NVMe
NAND 12
3.8


The most important and impressive indicator of solid state drives for consoles is the sequential read speed. The write speed to solid-state drives practically does not affect the performance of video games, and when games read data in blocks, their size is usually more than 4 kb - the volume at which the speed indicators of solid-state drives are calculated. Microsoft's 2.4GB / s read speed is 10-20x faster than a mechanical hard disk drive, but lags far behind current high-speed consumer SSD standards that can saturate PCIe 3.0 x4 with speeds of at least 3.5GB / s . Sony's 5.5GB / s is slightly faster than the current PCIe 4.0 SSD on the Phison E16 controller,but every competitor in the high-speed consumer SSD market is already preparing its own advanced solution. By the time it appears, the performance of SSDs in the PS5 will be unremarkable - it will match other advanced SSDs, and surpass only other consoles and low-cost PCs that do not fit in a budget with a fast drive.



Sony has revealed that their SSD uses a dedicated controller with a 12-channel NAND flash interface. This is probably the most important difference between their system and typical consumer solid state drives. Typically high-speed consumer SSDs use 8-channel controllers, while the simplest drives use 4-channel controllers. More channels are commonly found with server SSDs, especially those that require a lot of bandwidth. 16-channel controllers are more common, but there are 12 and 18-channel controllers. Sony's use of more channels than recent consumer storage devices means their controller will be unusually large and expensive. But on the other hand, they will not need each channel to be super fast, in order toto reach the goal of 5.5 GB / s. They can use any 64-layer TLC NAND and get adequate performance, while consumer SSDs trying to achieve this need to be paired with the newer and faster NAND flash.



The 12-channel controller also provides an unusually large maximum volume. The console solid state drive does not need to be much larger in volume than a typical consumer drive, so 50% more channels can mean 50% more volume. The PS5 will have "825 GB" of space, which means that each channel will be equipped with 64 GiB of NAND, organized either on one 512 Gb (64 GB) die, or on two 256 Gb (32 GB) chips per channel. This means that the nominal size of NAND will be 768 GiB, or 824.6 GB. The free space on it, excluding the reserved area, will most likely be the same as the space on the drives that the manufacturers write about "750 GB", so 825 GB from Sony is an exaggeration of more than 10% - and from any lawyer will get excited like that.



It's worth mentioning that it is unrealistic to expect Sony to develop its own high-speed NVMe controller - just like developing its own processor or GPU. She had to agree with an existing controller manufacturer and order a special controller for herself - probably made on existing technologies - however, we don’t know who exactly this partner is.



A solid state drive from Microsoft won't go beyond what's found on modern PCs. Today, SATA SSD for OEM has already passed, but a terabyte for PCs at the price of consoles will be quite an interesting offer for users. Various sources say that Microsoft decided to use a ready-made controller from one of the usual suspects (probably Phison E19T), and the drive itself is made by one of the major manufacturers. However, the company can still declare the use of a special form factor and, probably, special firmware.



None of the two companies shared information about the insides of their SSDs, except for the 12-channel controller from Sony, but their volume and speed give an idea of ​​what to expect from them. Sony decided to use TLC NAND, and Microsoft's slower target is more in line with QLC NAND. 2.4GB / s is slightly more than what we see with current 4-channel QLCs like Intel 665p (at around 2GB / s), but much less than 8-channel Sabrent Rocket QLCs. Q (3.2 GB / s for 1 TB model). A 4-channel drive with TLC NAND is best suited to Microsoft's description, however newer 4-channel controllers like the Phison E19T should support these speeds with the correct QLC NAND option. Any console can get a double speed version using QLC NAND in the near future.in order to achieve the same performance as the original models.



Without DRAM, so what?



Without specific indicators for writing and random reading, we cannot exclude the possibility of using DRAMless in any of the consoles .-controller. Including the flash translation layer (FTL) of a DRAM cache drive in tables basically increases performance in two ways: preventing a write speed drop when the drive is full enough to have to juggle data in the background, and increasing random access speed when reading data from all over drive. These two cases are not particularly suitable for consoles: they are focused on reading and accessing only one set of game data at a time. Even if the installation size of games reaches 100-200 GB, the amount of data used at one time by the game will not exceed a couple of tens of GB, and a DRAMless drive can easily cope with this if there is enough SRAM on the controller itself. In the case of Microsoft, the choice of DRAMless is very likely,and if in any other context it would be strange to see a 12-channel DRAMless controller, then for Sony this option seems suitable (and allows you to save money spent on multi-channel).



The aforementioned Sony patent details exactly how a DRAMless controller can be prepared for use in consoles. Instead of caching part of the FTL table of physical and logical addresses on the controller SRAM, Sony suggests making this table small enough to fit into the SRAM buffer. Typical SSDs for each TB of flash memory have 1 GB of DRAM. This is a direct consequence of the way FTL handles 4KB flash memory. Working with memory in larger blocks will reduce the memory requirements for storing the table. The downside is that writing small pieces of information will go slower. Western Digital sells a dedicated industrial solid state drive that uses 32KB instead of 4KB for FTL, and as a result needs eight times less DRAM.The random write speed of this SSD is terrible, but the read speed is competitive. Sony's patent suggests going far beyond 32 kB and using 128 MB blocks for FTL, which will reduce the size of the table to a few kilobytes. To do this, the system needs to carefully approach the question of what and when to write to the drive, but the reading speed that games rely on will not suffer from this.it will not suffer from this.it will not suffer from this.



In short, if a solid state drive from Sony will work very quickly in the intended modes, I’m ready to argue that you don’t want to install it on your Windows PC. The same will probably be true for solid state drives from Microsoft - depending on what kind of firmware they make.



Extensibility



Both Microsoft and Sony are offering options to expand NVMe storage in future consoles. Microsoft is going to make a special removable form factor for SSDs, reminiscent of those times when the cartridges for the consoles were changed in megabytes instead of terabytes, and USB flash drives were not common. Since all the components are the same, the expansion card will functionally be identical to the internal storage. The downside is that Microsoft will control the production and sale of such cards, which will affect their cost. So far, only Seagate is a confirmed sales partner for these proprietary expansion cards.



Sony does the opposite, and gives the user access to the standard M.2 PCIe 4.0 slot. Requirements are not entirely clear: Sony will be testing compatibility with third-party drives to publish a compatibility list, but they are not saying whether their console will reject non-listed drives. To get to the list, the drive must fit mechanically into the connector, and also offer performance no worse than Sony's internal drive. This means that so far none of the commercially available drives are suitable for this purpose, but the situation will change dramatically next year.



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