Xbox One Architecture Panel *Main Console HW Points* Transcript

[Deleted member 11852]

OSX's approach isn't at all conducive to the console space, however, where cost is a concern. It's a very simplistic and brute force way of doing it. Everything is just written to the SSD first, then moved to HDD either after a period of inactivity or if the SSD approaches a certain cutoff point (I can't remember offhand what that is). At which point files with the oldest access timestamp are moved to the HDD.

This isn't how Fusion works - I have two Macs with Fusion drives, one a 3Tb Apple 'Fusion Drive' and the MacMini server has a Fusion drive partition I created form a 2Tb HDD and 768mb SSD drive. The algorithm used by Fusion is laughably simple and is detailed on Apple's ADC website if you have a developer account, even a free one. In brief, when files are written out they will be earmarked either for the SSD or HDD, this is determined by several factors:

• The 'popularity' of the host application (i.e. Word, Excel, iTunes, Maya etc). New files inherit this.
• An assessment by the system on the performance-criticalness of the type of file.
• Free space on the SSD.

If all the entire filesystem fits on the SSD, everything goes on the SSD. Simple. Once the filesystem exceeds the SSD size the filesystem will begin applying the Fusion algorithm. MP3/AAC music files will rarely be earmarked for the SSD, nor will movies - unless they are being read/written huge amounts of times - which is where the 'popularity' angle comes in.

This determination by the filesystem is ongoing until a file is deleted. Where files are written initially depends on the determination and the available free space of the SSD. If it has plenty of space, they'll go there first then moved to the HDD in the background so that the user can continue with their work. If there isn't a lot of space they'll go to the HDD first. If that's where they are supposed to be they'll stay there, if Fusion wants the files on the SDD, it'll move stuff from the SSD to HDD to make room, then move the HDD stuff to the SSD.

It's as simple as that. And it works really, really well. It would work fine in a console. Things you want/need to read quickly go to the SSD, other things go to the HDD.

Re: flash cache vs hybrid HDDs...
Desktop operating systems are never fully aware of, or adapted to use flash

That approach basically requires a large SSD (128 GB minimum in order to be noticeably effective in all use conditions, and even then Anandtech found situations where it was inadequate and wished for a larger SSD) versus the 4-8 GB (HDD) or 20GB+ (Windows) for a flash cache.

More flash is always but you certainly don't need a minimum of 128Gb, the algorithm used by Fusion will adapt to any mix of HDD/SDD capacity and this is key because any OSX user can build a Fusion partition from any two internal drives in the system. Anand was simply saying the more SSD space you have, the more you'll benefit, which is obvious really.

I would be surprised if both new consoles don't have a smart filesystem capable or writing data for optimised reading. I also hope Sony have put in the little additional effort for SSDs as I'm sure a lot of owners will be wanting to slot one in. I have a spare 512Gb SSD earmarked for my PS4, assuming it's supported.

 

[Silent_Buddha]

It's as simple as that. And it works really, really well. It would work fine in a console. Things you want/need to read quickly go to the SSD, other things go to the HDD.

Yes, I didn't remember the exact details on it. I used a Mac for roughly a year recently and wasn't really my thing. To many small annoyances, although I did find some bits and bobs around the internet to alter some of the behavior to be more logical (to me).

I do like their Fusion system, however, and wouldn't mind seeing Microsoft implement something similar in Windows.

More flash is always but you certainly don't need a minimum of 128Gb, the algorithm used by Fusion will adapt to any mix of HDD/SDD capacity and this is key because any OSX user can build a Fusion partition from any two internal drives in the system. Anand was simply saying the more SSD space you have, the more you'll benefit, which is obvious really.

Sure, for a console depending on what it prioritizes, I could see 64 GB working or even 32. But when you start talking about Game files, 8 GB isn't going to cut it in any meaningful way without a lot of erase/write cycles which is going to tank the endurance of such a low capacity of NAND pool, especially if it is MLC manufactured on any recent process node.

That's where I was commenting on the feasibility with regards to consoles. It isn't going to be cost effective to include even a 32 GB SSD in addition to a large capacity notebook HDD currently, and even then I'd question the write endurance of a 32 GB MLC SSD if a user frequently alternates games. And 8 GB isn't going to be meaningful, IMO, for game cacheing. For apps or the OS on the other hand as I noted, it would be quite handy to keep the system feeling responsive anytime something is loaded. Especially, since then OS and app loading doesn't interfere with game access to the HDD. And the opposite being true as well where game access to the drive won't interfere with pulling up OS features or apps. Something that may or may not become frequent if game load times increase due to the increased fidelity of games.

I could see it becoming viable in the future as new SSD drive alternatives come to market. Samsung for example is saying that V-NAND will be cheaper, higher capacity, and have greater write endurance.

Regards,
SB

 

[Jay]

I have wondered if it could save last/most used games there also.
I'm talking game menus, game engine, etc but not assets. Maybe through DME for compression.
The benefit of it is quicker initial loading times, thereby making fast switching a lot more quicker, even for games.
Game itself can be loading last level assets in the background from HDD whilst you go through menus.

I'll not bother write out how I think it could be used, but it really could make a difference, and not just storing OS on.

 

[Deleted member 11852]

Sure, for a console depending on what it prioritizes, I could see 64 GB working or even 32. But when you start talking about Game files, 8 GB isn't going to cut it in any meaningful way without a lot of erase/write cycles which is going to tank the endurance of such a low capacity of NAND pool, especially if it is MLC manufactured on any recent process node.

8Gb is quite a lot if you're the type of person who plays one game at a time or plays one game a heck of a lot. Remember we're not talking about fitting the whole game into SSD, the consoles are desgned - I hope - to perform well with HDD. We're only talking about boosting that performance for the files that make the most difference to performance.

That's where I was commenting on the feasibility with regards to consoles. It isn't going to be cost effective to include even a 32 GB SSD in addition to a large capacity notebook HDD currently, and even then I'd question the write endurance of a 32 GB MLC SSD if a user frequently alternates games.

Agreed, NAND-based drives are too expensive to ship with the consoles but I'm just hoping the consoles support them so users have an upgrade path for those of us who're too old to wait for platters to spin!

 

[Silent_Buddha]

8Gb is quite a lot if you're the type of person who plays one game at a time or plays one game a heck of a lot. Remember we're not talking about fitting the whole game into SSD, the consoles are desgned - I hope - to perform well with HDD. We're only talking about boosting that performance for the files that make the most difference to performance.

The thing is, that as a hardware manufacturer, Microsoft can't just design the console in the hope that any given user will only use one game a lot and only infrequently switch games. They have to build with the expectation that some X number of people may use it in nearly the worst case scenario. Especially if you consider that many people may opt for DD only games for their library which makes it as simple to swap games as it is on PC.

Considering how they went to great lengths to prevent the user from somehow bricking their console due to insufficient ventilation, I highly doubt they would be cavalier about the write endurance of their NAND storage pool.

Agreed, NAND-based drives are too expensive to ship with the consoles but I'm just hoping the consoles support them so users have an upgrade path for those of us who're too old to wait for platters to spin!

Well, in that case just store your games on an external SSD. I doubt the OS or apps will be greatly hampered by the HDD speed, especially if those are kept and/or cached in the 8 GB of NAND.

Regards,
SB

 

[Deleted member 11852]

The thing is, that as a hardware manufacturer, Microsoft can't just design the console in the hope that any given user will only use one game a lot and only infrequently switch games. They have to build with the expectation that some X number of people may use it in nearly the worst case scenario.

Right, and I hope Microsoft have hit this design goal with the HDD supplied in the XBox One. What we're talking about, or what I'm talking about , is the potential benefit of throwing an SDD, or failing that, a hybrid into the mix - assuming disk I/O is a bottleneck.

If the Xbox One performs well with a [relatively] slow-ass HDD then it should perform better with some NAND/flash store, as long as the One itself is smart enough to make good use of it. Even a small amount, like 8Gb, would do wonders in the scenario I outlined. But more is obviously better. Ditto for PS4.

 

[Bigus Dickus]

This thread for some reason reminds me if playing Buck Rogers on a colecovision Adam computer... using a cassette tape drive. The game would pause at certain points and have to wait for the tape to rewind.

We've come a long way!

 

[Silent_Buddha]

Right, and I hope Microsoft have hit this design goal with the HDD supplied in the XBox One. What we're talking about, or what I'm talking about , is the potential benefit of throwing an SDD, or failing that, a hybrid into the mix - assuming disk I/O is a bottleneck.

If the Xbox One performs well with a [relatively] slow-ass HDD then it should perform better with some NAND/flash store, as long as the One itself is smart enough to make good use of it. Even a small amount, like 8Gb, would do wonders in the scenario I outlined. But more is obviously better. Ditto for PS4.

True, and considering that Microsoft has had experience with using USB flash drives for caching applications and data, it's certainly possible. But I somehow doubt they will go to the effort of implementing something similar to Apple's Fusion with an external SSD. Although that would certainly be quite impressive if they did.

Regards,
SB

 

[fehu]

True, and considering that Microsoft has had experience with using USB flash drives for caching applications and data, it's certainly possible. But I somehow doubt they will go to the effort of implementing something similar to Apple's Fusion with an external SSD. Although that would certainly be quite impressive if they did.

this feature would be spinned as "they sold us half a console and to have the complete experience you have to buy extra hardware"

 

[Deleted member 11852]

True, and considering that Microsoft has had experience with using USB flash drives for caching applications and data, it's certainly possible. But I somehow doubt they will go to the effort of implementing something similar to Apple's Fusion with an external SSD. Although that would certainly be quite impressive if they did.

I doubt very much Microsoft would implement a full Fusion implementation, that is allowing two completely separate drives to form a hybrid partition, but implementing the basic algorithm for existing hybrid drives isn't a big ask. It is, after all, a very basic 'policy decision' for the filesystem.