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PS5 SSD (no no, keep reading) has a DRAM cache

alabtrosMyster said:
So Microsoft complied a version of smartdrv.exe from their DOS days and called it a day.

That's not the same as having dedicated hardware to do the caching.

MS sells you a low end disk at a high end price... Then they claim OS level ram cache is the same as actual disk cache, well call Samsung, Western digital and many more to let them know because they have spent all that r&d money for naught for ages now.
Click to expand...

The use case for dram cache in hardware is extremely different for a pc and a console it really all depends on how the software is using the ssd access and honestly I have no problem that it's not there on the Xbox. thicc_girls_are_teh_best thicc_girls_are_teh_best is pretty spot on the money here.
 
I'm not sure what the latency and bandwidth is of SSD cache is, but GDDR is not low latency and not designed as cache.
 
mckmas8808 said:
How did this turn into a console war fight already?
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giphy.gif
 
LordOfChaos said:


www.psu.com

The PS5 SSD Seemingly Has DRAM Cache, Offers Benefits Over Xbox Series X SSD - PlayStation Universe

The PS5 SSD features a DRAM cache, which offers a lot of benefits for Sony's new home console. Get more info here.
www.psu.com


Yeah, SSD thread, but interesting detail noted in the teardown. On top of the sizable SRAM cache in the IO complex, the SSD itself has an adjacent DRAM cache, which can be used to cache reads and writes for closer to instant access, as well as keep access tables in it. The more you can "spool" may also reduce wear.
Click to expand...


If it's a DRAM chip it's probably used for write buffering. Maybe the VCR function.
I don't think any read cache is needed in console design, introduces more latency and no streaming reads benefit.
 
mckmas8808 said:
How did this turn into a console war fight already?
Click to expand...
99% of this forum spends more time talking about a product they will literally never buy, than the product they plan to buy, and would always have bought even if it was not a good option.

Also 99% of this forum just so happens to love every difference their chosen system has, and dislikes the way the other company did it.. even if in the past the situations were switched lol
 
IntentionalPun said:
99% of this forum spends more time talking about a product they will literally never buy, than the product they plan to buy, and would always have bought even if it was not a good option.

Also 99% of this forum just so happens to love every difference their chosen system has, and dislikes the way the other company did it.. even if in the past the situations were switched lol
Click to expand...

It's like this in any hobby or pass-time. Ford vs. GM vs. Mopar guys, Star wars vs. Star Trek, Coke vs. Pepsi, consuming soy products vs. just hanging yourself, etc.

You like what you like, and sometimes no matter the argument presented, you will never accept that the thing you like has any faults. Instead you get upset and seek out others that tell you what you want to hear or agree with you completely. Then you and your new group, powered by confirmation bias, work together to discredit the opinions of the other group who is doing the exact same thing.

The rest of us are fully aware that pretty much everything sucks at least a little bit.
 
That's very good. DRAM cache is very important in SSD. That's what I learned when looking to buy one not long ago. Many recommended I go for SSD with DRAM for quicker access and avoid ones without it.
 
DrScissorsMD said:
Because the tweet this entire thread is based on is framing DRAM as super important/high-end and then instantly saying "but Xbox doesn't have it".
Click to expand...

XBOX IS FUCKED NOW, pack it up boys!

It's exciting to predict winners from synthetic benchmarks of analogs and fanboi cum dreams but nobody is going "win" or "lose" this thing until 3-4 years into the machine's lifespans.

Seriously this is a small feature that might or might not benefit the way a closed system operates. We'll have to wait and see how long these SSDs last, this is kind of a scary aspect of this gen. SSDs do have an incredibly high number of writes and rewrites though.

Lets hope there's a solution for both consoles when your soldered on SSD has reached EOL. I guess the only thing is, you could somehow hope that they could transfer primary storage from the soldered drive to one of the removable ones, both machines have full bandwidth to their expanded storage solutions, perhaps this is why?
 
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The worst thing about this PS5 SSD is.......
I can't buy a second one to install in my PS5. At least not for a while. Hopefully when the market catches up they'll be available to buy.
 
So if the PS5 SSD has its own DRAM cache, im guessing they will mandate expansions cards to also have a DRAM cache of equal or similar performance.

Or is the DRAM cache on board for the internal and expansions NVMe?

Does anyone one know anything or are we just flinging shit at the each other and hoping some tastes good.
 
FrankWza said:
So, 30% more expensive? That's significant
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$2 is 100% more expensive than $1. "That's significant."

People like you who rationalize by manipulating perspectives are a joke tbh. Relative and absolute measurements both matter.

Here let me try...

Total PS5 SSD w DRAM = $500
Total PS5 SSD wo DRAM = $475

So, 5.2% more expensive? That's insignificant
 
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Black_Stride said:
So if the PS5 SSD has its own DRAM cache, im guessing they will mandate expansions cards to also have a DRAM cache of equal or similar performance.

Or is the DRAM cache on board for the internal and expansions NVMe?

Does anyone one know anything or are we just flinging shit at the each other and hoping some tastes good.
Click to expand...

From what I've read about DRAM I don't think you would want an SSD in the PS5 without it. Maybe it isn't an issue in slower drives but in the PS5 it could ruin it's performance since it has to spend more time searching for the data. Hence why it's vital in the PS5. Without it you would have to store the drive map elsewhere which can lead to stuttering.

Sony will give us a list of compatible drives so if DRAM less drives are not supported they will let us know.

FrankWza said:
The worst thing about this PS5 SSD is.......
I can't buy a second one to install in my PS5. At least not for a while. Hopefully when the market catches up they'll be available to buy.
Click to expand...

Evil Cerny strikes again.

njs5yz0sn8n41.jpg
 
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Black_Stride said:
So if the PS5 SSD has its own DRAM cache, im guessing they will mandate expansions cards to also have a DRAM cache of equal or similar performance.

Or is the DRAM cache on board for the internal and expansions NVMe?

Does anyone one know anything or are we just flinging shit at the each other and hoping some tastes good.
Click to expand...

good question. It won't matter for storage purposes though. Only if and when they allow PS5 games to play off of a seconddrive
 
TyphoonStruggle said:
$2 is 100% more expensive than $1. "That's significant."

People like you who rationalize their own points of view are a joke tbh
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Are you joking?
that's exactly what you did when you dropped to the lowest dollar amount possible. It's a 30% difference. That's significant. Unless you wouldn't like to be paid gross over net. Or would you rather pay $650 for a next gen console?
 
MasterCornholio said:
They should be giving us a list of compatible drives soon but I'm annoyed that they haven't yet.
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for ps5 play or for storage? I'm mostly disc so I'm not going to sweat it too much. I don't think I'm going to take the plunge until the drives that are comparable to this drive become available anyway. As far as I'm concerned, they appear to have done everything that was a concern and really spared no expense. The more you read about the included components it's obvious they didn't cut costs or corners anywhere. We'll see when we have the systems in our hands. But I think they earned a little slack. 99+% PS4 BC, a future proof SSD, the cooling system all for $400 or $500 plus 2 awesome launch day titles. Yeah, they earned some slack.
 
Black_Stride said:
So if the PS5 SSD has its own DRAM cache, im guessing they will mandate expansions cards to also have a DRAM cache of equal or similar performance.

Or is the DRAM cache on board for the internal and expansions NVMe?

Does anyone one know anything or are we just flinging shit at the each other and hoping some tastes good.
Click to expand...

NVME drives with DRAM have the DRAM on the drive itself.

WD says that their SN850 is compatible with PS5. They did not mention if it has any DRAM or not, but its predecessor, the 750, does have DRAM.


The WD Black SN750 uses a 64-layer, 3D NAND, triple-level cell (TLC) design and 256MB of DRAM cache for every 250GB of capacity. Simply put, our WD_BLACK SN750 NVMe SSD is screamin' fast!
Click to expand...
 
FrankWza said:
for ps5 play or for storage? I'm mostly disc so I'm not going to sweat it too much. I don't think I'm going to take the plunge until the drives that are comparable to this drive become available anyway. As far as I'm concerned, they appear to have done everything that was a concern and really spared no expense. The more you read about the included components it's obvious they didn't cut costs or corners anywhere. We'll see when we have the systems in our hands. But I think they earned a little slack. 99+% PS4 BC, a future proof SSD, the cooling system all for $400 or $500 plus 2 awesome launch day titles. Yeah, they earned some slack.
Click to expand...

I meant the internal drive. However if you can just back up PS5 games on an external I might do that since it has USB 3.1 so transfers should be quick.
 
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Kerlurk said:
from reddit (PS5 devkit PCB specs from OQA):


  • monolithic die ~22.4mm by ~14.1mm
  • 16 Samsung K4ZAF325BM-HC18 in clamshell configuration
  • memory vrm seems like overkill with multiple Fairchild/ON Semiconductor FDMF3170 power stages controlled by an MP2888 from MPS
  • 3 Samsung K4AAG085WB-MCRC, 2 of those close to the NAND acting as DRAM cache (unusual 2GB DRAM per 1 TB NAND)
  • 4 NAND packages soldered to the PCB which are TH58LJT2T24BAEG from Toshiba
  • PS5016-E16 from Phison
Samsung memory chip used as cache in the SSD
https://www.samsung.com/semiconductor/dram/ddr4/K4AAG085WB-MCRC/
Density16 GbOrg.2G x 8
Speed2400 MbpsVoltage1.2 V
Temp.0 ~ 85 °CPackage78FBGA
Product StatusMass Production

The PS5 reveal shows only a single DRAM chip present, so 2 GB of cache is part of the SSD system in the PS5 (???).

Speed is 2400 Mbps. That's only 300 MB/sec. The SSD is rated at 5.5 GB/sec. (???)

Anyone have any ideal how that works?
Click to expand...



I think the important thing for DRAM to contribute in an SSD is the difference in latency, it's nanoseconds vs microseconds, a 1000x difference. So by placing lookup tables in DRAM, from the perspective of the SSD table lookups are nigh instant. And DRAM is truly flexible and random access - any data, any time, where NAND is only great at parallel accesses. A DRAM cache buffers the multitude of random and chaotic incoming write requests and coagulates them in to large work chunks that are optimized for maximum write efficiency to the flash cells. This increases the overall smoothness of the SSD and consistency of responsiveness. One of the hallmarks of a DRAMless SSD is that it tends to stutter when forced under heavy loads or concurrent requests. This is what DRAM helps with in SSDs.

DRAMvsNAND.png


If you look through the Sony patents leading up to this it was pretty clear they were trying to bridge the gap between storage and a deterministically fast media, so the DRAM was a must.
 
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Kerlurk said:
Anyone have any ideal how that works?
Click to expand...

I don't think you are supposed to compare the raw bandwidth of the two, the cache is just to avoid accessing the much more complex and slower storage in the SSD. It is mroe about access time and latency.

What is the Host Memory Buffer in NVMe SSDs and How Does it Work?

The NVMe 1.2 specification introduced a new feature called Host Memory Buffer or HMB (not to be confused with HBM graphics memory), with the promise of dramatically improving the performance of PCIe NVMe SSDs. In this article we explain what it is, how it works, and how it manages to improve the...
itigic.com itigic.com

The standard DRAM to NAND ratio we have discussed provides enough RAM to the SSD controller to use a very agile quick lookup table, rather than using more complex data structures that would be significantly slower. This dramatically reduces the work that the SSD controller has to do to perform input and output operations, and is the key to consistent performance.

Non-DRAM SSDs can be quite cheaper and even smaller, but since they can only store data index tables in internal flash memory their performance is quite penalized. In the worst case, the reading latency can be doubled since each reading operation will require one operation to know where the physical data is, and another one to read the data itself.
Click to expand...
 
LordOfChaos said:


www.psu.com

The PS5 SSD Seemingly Has DRAM Cache, Offers Benefits Over Xbox Series X SSD - PlayStation Universe

The PS5 SSD features a DRAM cache, which offers a lot of benefits for Sony's new home console. Get more info here.
www.psu.com


Yeah, SSD thread, but interesting detail noted in the teardown. On top of the sizable SRAM cache in the IO complex, the SSD itself has an adjacent DRAM cache, which can be used to cache reads and writes for closer to instant access, as well as keep access tables in it. The more you can "spool" may also reduce wear.
Click to expand...


 
This is like Soviet Propoganda machine. 😂

There are many custom controllers used in embedded systems ( like consoles ) which do away with requirement for an SSD's DRAM. It requires a sufficient bus bandwidth and a custom firmware and driver, hence you do not see it in assembled systems (like PC). According to the below article, it is quite a fast solution and provides a cost advantage over SSD with DRAM.
Anand-Tech, Host Memory Buffer Controllers
 
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).
Click to expand...
Add to the OP.
 
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NXGamer said:
Perfect use man, Bravo!

I think this is actually DDR, which makes a great deal of sense as the Kraken Decom resides within the SSD and this is a close cache for that to work on the data sets and Table Mappings etc.
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Isn't the Kraken decompression chip in the I/O complex within the APU as seen in road to PS5 diagram?
 
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Anything that makes the system better is appreciated...I'm sure most rational gamers would agree.....
Concern said:
Some people can't make a thread about one console without trying to shit on the other. Another good example was the wifi6 thread.

thicc_girls_are_teh_best thicc_girls_are_teh_best makes an informative post and is attacked.
Click to expand...
An informative post is subjective and it's really an "in the eyes of the beholder" judgement call. This is a discussion forum, you argue for against points raised, that's how it works, so you thinking that everyone should agree with a certain poster, when there are several flaws and disingenuous takes in his argumentation is not exactly how things should happen, just because you agree, does not mean others do or should. So yes, I see no scenario where dram is bad for an SSD, if anything it will have advantages in certain scenarios as opposed to pooling that ram elsewhere...
 
Lysandros said:
Isn't the Kraken decompression chip in the I/O complex within the APU as seen in road to PS5 diagram?
Click to expand...
It is, but using the SRAM to decompress ALL the data on Chip would be excessive.

This may be a block used for OS reserve/Decom etc. I think it is used as some form of data cache for the system, the question is what.

If we look at Pro, they added a block of 1GB DDR3 to handle the OS/4K UI. This seems like a similar block for a similar use, it is why the Pro provides 512GB of GDDR5 over base.
 
NXGamer said:
It is, but using the SRAM to decompress ALL the data on Chip would be excessive.

This may be a block used for OS reserve/Decom etc. I think it is used as some form of data cache for the system, the question is what.

If we look at Pro, they added a block of 1GB DDR3 to handle the OS/4K UI. This seems like a similar block for a similar use, it is why the Pro provides 512GB of GDDR5 over base.
Click to expand...
I see, thanks for the reply. Interesting, so you think the chip in question is DDR instead of DRAM and it's used as cache/memory (OS etc.) hybrid, correct?
 
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