Digital Foundry Article Technical Discussion [2021]

[London Geezer]

Still doesn't explain the numbers that the PS5 throws out when testing the drives. They seem to have no relevance to the speed of the actual drive?

 

[Nesh]

Maybe its counting the uncompressed value of compressed data that are streamed into the drive and not the performance of the drive?

 

[goonergaz]

Still doesn't explain the numbers that the PS5 throws out when testing the drives. They seem to have no relevance to the speed of the actual drive?

Yeah, from memory my 850 was only 5,600.

This thing is, the data transfer tests show that the 750 is significantly slower, but fast enough for current games…as I believe it’s suggested above, the I/O system by Sony is probably helping a lot.

At the end of the day, each to their own, but I’m not risking a 750 long term - if buying one it’s be with the mind that it will need upgrading at some point.

 

[see colon]

Maybe its counting the uncompressed value of compressed data that are streamed into the drive and not the performance of the drive?

Wouldn't that make the faster drives even faster? The slow drive benches above spec and the fast drive benches below spec. That's why the numbers don't make sense.

 

[goonergaz]

Wouldn't that make the faster drives even faster? The slow drive benches above spec and the fast drive benches below spec. That's why the numbers don't make sense.

Stupid question, the 750 was supplied by someone…can DF be 100% certain someone isn’t playing a trick?

 

[chris1515]

Wouldn't that make the faster drives even faster? The slow drive benches above spec and the fast drive benches below spec. That's why the numbers don't make sense.

Numbers are higher for faster drive. Other things, hardware decompressor is tailored for 5,5 GB/s drive maybe it will be the bottleneck for 7GB/s drive.

EDIT: If 850 is only 5600 there is a problem into storage measurement.

 

[Allandor]

Still doesn't explain the numbers that the PS5 throws out when testing the drives. They seem to have no relevance to the speed of the actual drive?

I guess their test-setup has a bug here. I guess they write a "file" and try to read it as fast as it can. But if the SSD has some cache (e.g. RAM) than the result you get is how fast the cache on the SSD is and not how fast the SSD really is.
You can make such a bench with the PS5 SSD as there is no cache in between. But on a SSD with Cache the data is first written into the cache and than into the much slower cells. When you now directly read the data, the data is copied from the cache itself. This would work with Test-Data that is bigger than the cache, but I guess as the write-speed of the PS5 SSD is really low, they won't write such big data files for testing.
With bigger test-files you should see that the first few ms you get a big load of data and than it get's much slower as the data is no longer cached.

 

[Arwin]

Or the drive really is performing 5GB/s on the PS5, just as the PS5 itself reports, and as the developer now reports as well.

 

[BRiT]

Or the drive really is performing 5GB/s on the PS5, just as the PS5 itself reports, and as the developer now reports as well.

Naaaaaaaaaaaaaah.

 

[PSman1700]

I think the SSD and compression tech is just too over blown.

Its where we got a large leap, to no surprise its that what is being hyped.

I guess their test-setup has a bug here. I guess they write a "file" and try to read it as fast as it can. But if the SSD has some cache (e.g. RAM) than the result you get is how fast the cache on the SSD is and not how fast the SSD really is.
You can make such a bench with the PS5 SSD as there is no cache in between. But on a SSD with Cache the data is first written into the cache and than into the much slower cells. When you now directly read the data, the data is copied from the cache itself. This would work with Test-Data that is bigger than the cache, but I guess as the write-speed of the PS5 SSD is really low, they won't write such big data files for testing.
With bigger test-files you should see that the first few ms you get a big load of data and than it get's much slower as the data is no longer cached.

5GB/s before compression.

 

[Silent_Buddha]

I guess their test-setup has a bug here. I guess they write a "file" and try to read it as fast as it can. But if the SSD has some cache (e.g. RAM) than the result you get is how fast the cache on the SSD is and not how fast the SSD really is.
You can make such a bench with the PS5 SSD as there is no cache in between. But on a SSD with Cache the data is first written into the cache and than into the much slower cells. When you now directly read the data, the data is copied from the cache itself. This would work with Test-Data that is bigger than the cache, but I guess as the write-speed of the PS5 SSD is really low, they won't write such big data files for testing.
With bigger test-files you should see that the first few ms you get a big load of data and than it get's much slower as the data is no longer cached.

The cache will help with writes, but it does virtually nothing for reads. So that wouldn't help explain why the read test on PS5 is so far above the rated speed of the drive. And just in case people think the read speed is underrated by the manufacturer, it isn't. The drive is popular and has been reviewed extensively at many sites. For example, WD Black SN750 NVMe SSD review: Faster than ever, and still a fantastic bargain | PCWorld .

So, it does have 256 MB of DRAM cache (256 MB per 250 GB of capacity), however, that is for caching writes as there is no reason to cache reads. IF you could somehow read out of the DRAM cache, then it would be significantly higher than 5 GB/s. Basically it would saturate the NVME link.

But that's a moot point as the DRAM caches on SSDs aren't readable since they are there purely to cache writes.

Regards,
SB

 

[eastmen]

But 56gb wasn’t possible this gen due to price? And what’s to say SSD won’t come down or even RAM costs go up?

Your views are just far too narrow minded and not considering the bigger picture.

Ive said countless times that part of the SSD upgrade was to remove that headache for the developers yet you keep putting it back in.

So now open world games will need to have fairly similar looking ‘jump to’ points - great.

You need to open your mind to what possibilities SSD allow rather than downplaying and sticking to ‘how we’ve always done it’. This is the biggest advancement in loading speeds for many generations, it changes the way games can be designed, it’s big.

It was a while until a majority of games required 3D cards, but those were also different times, these days games are costing significantly more to produce and therefore limiting audience is not the greatest idea.

The scenarios you pick suit what you want. SSD prices come down while ram goes up ? ITs doubtful to say the least it can just as easily be the other way around. We also have ddr 5 coming out that will increase the minimum ram on each dimm while doubling performance.

SSD was to cover for the fact that ram size barely increased since last gen even though these new machines target 4k while the old 1080p.

There is no need for jump points to look the same , you can still create things that look different despite using repeated textures esp with machine ai being to change them while they are in memory. The first example from sony with ratchet and the portals can be done with more ram just like it was done with an ssd.

We get games limiting what machines people need all the time. Ray tracing is an example of that continuing. Next gen consoles are barely able to do it and graphics cards capable of it are still expensive and if you want to move to 4k for it then even more expensive. Your look at $800+ with MSRP pricing to even hvae a chance at 4k ray tracing without having to use an upscaling option

 

[eastmen]

Yeah, from memory my 850 was only 5,600.

This thing is, the data transfer tests show that the 750 is significantly slower, but fast enough for current games…as I believe it’s suggested above, the I/O system by Sony is probably helping a lot.

At the end of the day, each to their own, but I’m not risking a 750 long term - if buying one it’s be with the mind that it will need upgrading at some point.

By the time nvme speed drives are required on the pc your going to have PCI-E 5 drives at much faster speeds anyway

Its where we got a large leap, to no surprise its that what is being hyped.



5GB/s before compression.

Yea it just seems odd , oh this drive suddenly got faster on consoles and its totally better than having this other storage that is multiple times faster.

 

[PSman1700]

Yea it just seems odd

Doesnt it make sense though? When they test this low end drive (3.5gb/s read) on pc i assume thats before/without compression like rtx io and direct storage?

oh this drive suddenly got faster on consoles and its totally better than having this other storage that is multiple times faster.

Faster than what, this WD black drive being discussed? Yeah, should be. Samsung's 980 pro does +7000mb/s write, approaching PS5's SSD with compression tech (879gb/s) which the pc platform is lacking atm.
Main ram is in a total different universe, heaps faster in raw speeds but latency etc.

Anyway, as per the discussion on what is 'better' to have, main ram, or a fast ssd etc for streaming, i think ideally you'd want both. 7+GB/s ssd and compression lifting that atleast the double of that and 16gb's of fast main ram/12gb gddr6 vram etc. Would like to see how a FS or GTA game could take advantage of that.

 

[goonergaz]

The scenarios you pick suit what you want. SSD prices come down while ram goes up ? ITs doubtful to say the least it can just as easily be the other way around. We also have ddr 5 coming out that will increase the minimum ram on each dimm while doubling performance.

SSD was to cover for the fact that ram size barely increased since last gen even though these new machines target 4k while the old 1080p.

There is no need for jump points to look the same , you can still create things that look different despite using repeated textures esp with machine ai being to change them while they are in memory. The first example from sony with ratchet and the portals can be done with more ram just like it was done with an ssd.

We get games limiting what machines people need all the time. Ray tracing is an example of that continuing. Next gen consoles are barely able to do it and graphics cards capable of it are still expensive and if you want to move to 4k for it then even more expensive. Your look at $800+ with MSRP pricing to even hvae a chance at 4k ray tracing without having to use an upscaling option

The scenarios who picks? Are you suggesting I’m picking examples that suit my argument like you are? Actually I want to see something that I can’t imagine being created because it wasn’t possible last gen…The speed of these SSDs opens those possibilities, extra RAM is just more brute force to ‘the way we always did it’ - it’s not progressing.

My point regarding price was just that, it could go either way. Why don’t we have more RAM this gen? Price I believe.

Your muddling the water with required vs extra features…I can’t think of any games that require RT!?

 

[see colon]

I guess their test-setup has a bug here. I guess they write a "file" and try to read it as fast as it can. But if the SSD has some cache (e.g. RAM) than the result you get is how fast the cache on the SSD is and not how fast the SSD really is.
You can make such a bench with the PS5 SSD as there is no cache in between. But on a SSD with Cache the data is first written into the cache and than into the much slower cells. When you now directly read the data, the data is copied from the cache itself. This would work with Test-Data that is bigger than the cache, but I guess as the write-speed of the PS5 SSD is really low, they won't write such big data files for testing.
With bigger test-files you should see that the first few ms you get a big load of data and than it get's much slower as the data is no longer cached.

Didn't Richard say the slower drive didn't have a dram cache, though?

 

[eastmen]

The scenarios who picks? Are you suggesting I’m picking examples that suit my argument like you are? Actually I want to see something that I can’t imagine being created because it wasn’t possible last gen…The speed of these SSDs opens those possibilities, extra RAM is just more brute force to ‘the way we always did it’ - it’s not progressing.

My point regarding price was just that, it could go either way. Why don’t we have more RAM this gen? Price I believe.

Your muddling the water with required vs extra features…I can’t think of any games that require RT!?

Again hard drives have always gotten faster. We've had sata ssd's multiple times faster than the hard drives available in last gen systems for what 5 or 6 years before last gen systems even came out. Faster storage isn't an new thing. But what is different this generation is that ram didn't go up in size like it used too. So now everyone is trying to hype up faster storage speeds. If the systems came with 24 or 32 gigs of ram no one would be gushing over these ssds which also exist in computers and have for years.

 

[chris1515]

Again hard drives have always gotten faster. We've had sata ssd's multiple times faster than the hard drives available in last gen systems for what 5 or 6 years before last gen systems even came out. Faster storage isn't an new thing. But what is different this generation is that ram didn't go up in size like it used too. So now everyone is trying to hype up faster storage speeds. If the systems came with 24 or 32 gigs of ram no one would be gushing over these ssds which also exist in computers and have for years.

Again SSD main gain is fast loading. And this is very good to load in 1 second much better than have a long loading at the beginning of the game. Here NVME SSD gives fast loading and for dev it means the RAM is more useful. They don't use it as much as data cache with most of the RAM with non useful data like last gen. Having less RAM and faster storage and slower storage and more RAM is inferior to the first solution because slower loading time is not a good solution even if it only at when start the game. On commercial website, they discover than people quit the site if they need to wait more than 4 seconds. Basically any loading time more than 4 seconds is too long.

Microsoft, Sony and the devs said the same thing, it means fast loading and better assets quality because they aren't constrained by the streaming system.

The only innovation is the I/O hardware and software stack on consoles.

 

[Deleted member 11852]

Using the Steam Survey is a bit of a problem at times for these kinda things because it encompasses soooooo many PCs. So many of which are not at all even in the starting demographic of people interested in "high end" experiences. So when there is like 2% something on the Steam Survey, it can mean multiple millions of devices as a representation.

And not to forget that people are increasingly using low-end PCs as a host to stream their gaming from better hardware. I do this on my laptop, streaming locally both from my PC and my PS5. That said, the Steam hardware survey data is the biggest maintained data pool there is. It would be nice if Steam could let you dissect the data based on the types of games being played on the actual hardware, or discount hardware that is not actually running games at all, but here we are.

Yeah, from memory my 850 was only 5,600.

My 2Tb SN850 with stock cooler reported a read speed of "6541.3 MB/s" in the second beta firmware. I took a picture, I don't know why. I'm weird like that.

Performance can vary - not massively, but also not insignificantly - based on the NAND cells, the performance of the controller which can be predicated on it's thermal characteristics and the read/write patterns, noting that write strategies are purposefully designed to throw a little randomness to increase cell lifespans. Then toss in that the drive itself isn't 'dumb' and undertakes periodic read/writes on data to ensure integrity you have a lot of factors that can introduce variations in actual performance.

 

[Nesh]

Again hard drives have always gotten faster. We've had sata ssd's multiple times faster than the hard drives available in last gen systems for what 5 or 6 years before last gen systems even came out. Faster storage isn't an new thing. But what is different this generation is that ram didn't go up in size like it used too. So now everyone is trying to hype up faster storage speeds. If the systems came with 24 or 32 gigs of ram no one would be gushing over these ssds which also exist in computers and have for years.

We didnt have SSD's implemented by default with high efficiency controllers and games developed around that idea before. Actually you should thank consoles because they bring up solutions that can benefit the PC space where brute force is the norm and games are made around the idea that there are weak systems they need to support with simple downgrades.
Trying to spin the SSD in consoles to sound like nothing more than a storage to load games faster is very far from reality.
Even if you had 32GB of ram on PS5 a fast SSD opens up hugely what can be done with those 32GBs