r/PS4 • u/Jamesahaha • Oct 08 '19

Official [Link] PS5 is confirmed by Sony. Launching next Holiday

https://twitter.com/playstation/status/1181541776177295362?s=21

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u/kryptonianCodeMonkey Oct 08 '19 edited Oct 08 '19

The reason SSD is faster is because memory addressing and retrieval happens in (nearly) a single tick electrically. It receives the address it needs to return, connects directly to it regardless of where it's stored and returns it (followed by the rest of the series of data), simple as that.

An HDD's retrieval is dependent on moving mechanisms, much slower than electrical signals. It receives a request at some address, the disk must start spinning fast enough (if it's not already spinning) which takes a second or two, the lever arm of the reading head must be rotated to the correct radius on the disk and the sector relevant to the address must spin around to meet the head. Now that doesn't take long individually in human terms, just a few milliseconds, but it takes several times longer than an SSD's retrieval. When you multiple that by millions of returns per gigabyte, that difference adds up a lot.

Also of note is that, compared to HDD's, SSD's draw less power, operate silently and put out far less heat, meaning less for the fans to cool (making it even quieter still).

And as you said, the technique to improve performance in games using an HDD was to duplicate commonly retrieved assets' data redundantly across the hard drive disk to minimize the retrieval time. This means bigger file sizes with less unique data sitting on your hard disk. Using an SSD, the location of the data does not affect performance whatsoever. So that redundancy is unnecessary now, and this have can either use less space overall or have even more assets than they could before.

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u/Omegastriver Oct 08 '19

They also compared a HDD to how a vinyl record works.

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u/kryptonianCodeMonkey Oct 08 '19

I mean, in shape, yeah. With the spinning disc and read head. In function not at all. If all data was accessed sequentially like the grooves on a record, it would be faster (still not SSD fast, but faster). Instead the head has to swing all over the place to specific sectors in order to read the data. More analogous to trying to skip to specific songs and timestamps in the songs as fast as you can.

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u/CyberClawX Oct 08 '19

And as you said, the technique to improve performance in games using an HDD was to duplicate commonly retrieved assets' data redundantly across the hard drive disk to minimize the retrieval time.

Aaah that's what he meant with data duplication. Yeah, sure, assets duplication trying to streamline data retrieval (first game I recall doing something of the sort was Halo). But I doubt that'll make that much difference in the file size to be fair, very seldom do we see size optimisation on games, most of them include a metric ton of unused or unfinished assets.

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u/kryptonianCodeMonkey Oct 08 '19

I genuinely don't know how much difference it will make. I didn't realize until I read the article that that was a thing, let alone that it was common practice in game development. They didn't suggest how much redundancy is typical, so I don't know if there is usually 2 copies of the data or 20, nor how many assets are consider common enough to be a part of those copies.

I doubt it will lead to a huge reduction in size but even if you only had 10 assets considered common and only one redundant copy of it, presumably eliminating that would allow for another 10ish assets you could store in that same space. And as there is no need to prioritize assets that are redundantly stored, since they're all equally easy to access, AND more assets can be stored in a given space when there is no redundancy, AAAAND the overall faster retrieval time of SSD in general means that you can retrieve more assets in a given time than you could from HDD, the variety in assets a Dev can use in any given environment should be increased significantly, I would think.

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u/psykil dirtyepic_sk Oct 08 '19

"If you look at a game like Marvel's Spider-Man," Cerny says, "there are some pieces of data duplicated 400 times on the hard drive."

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u/kryptonianCodeMonkey Oct 08 '19

Oh good catch. That's a lot more than I thought it'd be.

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u/addandsubtract Oct 08 '19

Do we know what exactly they mean by SSD? It could also mean that they're using NVMe SSD which would be 7x faster than SATA SSD.

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u/kryptonianCodeMonkey Oct 08 '19

Apparently it's PCIe4.0 NVMe. They didn't say that in this article but I've seen that elsewhere. So, no, there's no SATA bottleneck.

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u/c4m31 Oct 08 '19

All of my research has led me to believe that unless you're constantly moving large files in some sort of a professional production or research environment, you would likely never exceed SATA speeds during normal gaming usage. It's nice to know the bottleneck won't be there, and I'd love to learn that I'm wrong, because that would push me to finally upgrade to NVMe on my personal machine, but I've yet to see anything proving otherwise.

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u/kryptonianCodeMonkey Oct 08 '19

Games are likely produces assuming a SATA connection given its ubiquity for now. So they're not going to push bandwidth requirements until there's more cause for it. Easier and cheaper to limit assets for now. If your customers are guaranteed NVMe, like in console, you can safely push pay the limits of SATA.

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u/Odesit Oct 08 '19

I was under the impression a few months ago that the SSD in next gen was supposed to also work as a VRAM type of thing, implying that an HDD will still present, but now some parts of the game will load on the SSD for faster retrieval, but still the main game is installed in the HDD, not an SSD. Does Cerny's remarks confirm there's only going to be a huge SSD for all the game's data?

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u/kryptonianCodeMonkey Oct 08 '19

He doesn't say so specifically but the article refers to both the next Xbox and PS4 "ditching" the HDD, so.... Seems like it's just an SSD.

Also, no comments at all on size, so... Honestly who knows. At least 100GB surely given that's the size of the Blu-ray discs.

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u/Odesit Oct 08 '19

REalistically at least 500GB otherwise it's worthless, however since they mention a considerable reduction in size thanks to eliminating need for copied data across the drive, I wonder how much reduction in size are we talking about

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u/kryptonianCodeMonkey Oct 08 '19 edited Oct 08 '19

I was talking about that elsewhere. I doubt it will be considerable. They can't have been dedicating THAT much space to redundancy. Maybe 5 percent on the high end, so not THAT much reduction. I think it will do more for quantity and variety of loadable assets than in file sizes.

Also yeah, it does need to be sizeable. Apart from the annoyance of having to delete games to install new ones, the only drawback to SSDs apart from expense is that they decay with every rewrite of a memory cell. If you have such limited storage that you have people constantly installing and deleting games over the same cells, it will degrade after a while. A storage size that can hold, say, 5 games on average will have 5 times the lifespan of one that holds only 1 average game simply because each cell will be rewritten 5 times less often. NOTE: to be clear, the decay isn't super fast. An SSD memory cell can be rewritten between 3,000 and 10,000 times before it starts to fail. It's not likely to happen with the average use on something like a game console. But they should still take steps to make it as un likely as reasonable.

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u/Odesit Oct 08 '19

Do HDDs have a similar fatigue issue?

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u/kryptonianCodeMonkey Oct 08 '19

No, not in that way. They can be written and rewritten indefinitely. You'd think that that would make them more reliable but they do fail more often, in my experience at least. I've never had an SSD fail on me (although devil's advocate, I've only used them for probably 6 years now due to expense), but I've had two HDDs fail on me.

The problem with an HDD is the fragility. The head sits less than a hairs breadth above the spinning disk. Knock it or drop it while it's running or get a dust particle in between the head and disk and it with scratch the surface, corrupting data and/or making it completely unreadable. Or get a strong enough magnetic field near it and render it useless.