It could be mostly read from in a console too. You'd only run into some trouble after you've loaded your 20,000th or so game? Edit: Wow I was probably an order of magnitude off there.
What is the write edurance like on these things nowadays?
Xbox One Architecture Panel *Main Console HW Points* Transcript
- Thread starter Warchild
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It could be mostly read from in a console too. You'd only run into some trouble after you've loaded your 20,000th or so game? Edit: Wow I was probably an order of magnitude off there.
What is the write edurance like on these things nowadays?
I'm not that familar with these, but cant you do anything on the flash based consoles as you can with one with an HDD?
That 12GB PS3 for example, surely you can install games to it? (Otherwise that model is useless)
Yes, but once you've downloaded a game, it's on there. You aren't rewriting that data constantly. With an HDD cache, every time you change game or area, if that data is not already in cache than you have to write to the flash. With the video streaming there's even the potential for constant writing to flash, depending on where that happens (the primary concern regards flash mem for a video cache).
Michellstar
Regular
Can part of the game data load directly from HDD or in this case flash--> to esram without touching main ram??
The whole point of a flash cache is to store data that needs to be constantly read not written. And given that there are "everyday use" products that solely depend on flash for storage, I doubt you have to worry about a console thats has a HDD to accommodate a bunch of random writes.
Furthermore, since the Xbox one's fact sheet already states that the system software takes up a significant amount on the HDD and the Xbox One is a multiple power state device, I highly doubt the OS is stored in the flash.
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As long as those write bypass the flash, yes. Take something like Oblivion for example. Every change the player makes is recorded on the HDD. If the HDD IO cache is in flash, every change would involve a write to the flash. You'd need to specifically bypass the flash caching the write data and write it to HDD knowing it won't be accessed for a while as that data is in RAM in the immediate location. But then every time you change town, you'd have the HDD access more data and that'd still be written to flash cache. With PRTs, the data on the flash will be constantly changing, though I don't know with what fequency. This is different to "everyday use" products that run directly from flash because the data is complete in the cache and doesn't need to be constantly replaced. That can't be done with 50 GB games and an 8 GB flash store, so there will inevitably be a constant change of content on the flash for the immediate game.
Aren't those Oblivion world changes resident in memory in the growing save file, which caused problems for the PS3 game (actually that was Skyrim). They only write to the HDD with a game save?
It should be simple enough to not write the game save to flash.
It should be simple enough to not write the game save to flash.
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Maybe, but it's only presented as an example of why flash cache for an HDD is incomparable to a flash-based device. With HDDs as standard, all games copied to HDD instead of run from disc, PRT and the potential for live data to be recorded, HDD write requirements are going to reach their zenith, and any flash sitting between the system and the HDD is going to have to be cleverly handled if it's going to be caching data. That's one reason why using the flash just for OS makes some sense.
Furthermore, is there reason not to put the OS on flash? Considering so many devices do run the Os from flash, it seems odd for a system with flash and an HDD to put the OS on the slow HDD and use the flash purely for caching. PS3 and Wii and Wii U and 360 had OS on flash. Would be very odd by comparison for MS to not use the flash for that purpose.
OS in flash makes a lot of sense. You'll get quick boot times and quick loading of any OS-level features, like the game DVR (minus the clips stored on disc), all of the TV stuff etc. I imagine the browser could load from flash but cache to HDD as well. The hybrid drive doesn't make a lot of sense to me for a console.
I'm still hoping I'll be able to install games to an external SSD.
I'm still hoping I'll be able to install games to an external SSD.
Furthermore, is there reason not to put the OS on flash? Considering so many devices do run the Os from flash, it seems odd for a system with flash and an HDD to put the OS on the slow HDD and use the flash purely for caching. PS3 and Wii and Wii U and 360 had OS on flash. Would be very odd by comparison for MS to not use the flash for that purpose.
Yeah. If you have a multiple state device thats hardly ever completely shut down, whats the point of storing the OS in flash? You only accommodating a small percentage of cases where the console is completely shut down but you chewing through 40% of your flash instead of <1% of the HDD. Storing the OS in flash on previous gen console makes sense because they weren't design to be very accommodating from a noise or energy consumption standpoint.
Plus, its already a known that the system software is stored on the HDD.
Xbox One flash interfaces to the SB through an MMC while the HDD goes over a SATA 2, so its not evident that all HDD i/o is going through the cache. Furthermore some Flash caches have a write around mode where only reads are cached and all writes initiallly go to HDD. However, I am not sure how the Xbox One generates a working set for games.
There is a possibility this is a holding area for suspended games and app. MS might deploy the cache and the compression logic to allow multiple apps and games to exist in the background.
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Thought that was already confirmed...
http://www.engadget.com/2013/05/21/xbox-one-hard-drive/
Tommy McClain
D
Deleted member 11852
Guest
OSX understands NAND drives. Apple's approach to hybrid drive is 'Fusion' which is pairing a hybrid drive (or two completely different drives setup as a single volume) and special approach to volume and filesystem management. It's not rocket science, it's just Apple did it first. Anandtech did a nice piece on it.
Sure it's big for an OS today. But 6-8 years from now? I dunno.
I really think the big OS reservations in the main RAM and potentially the size of this flash memory is so that they won't run into constraints as they want to add features over the lifetime of the device.
Silent_Buddha
Legend
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.
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.
Of course, for Windows, the flash cache is generally recommended to be 20 GB or larger due to concerns over the frequent writes to the cache.
Hence, I find it unlikely that the 8 GB of flash in the Xbox One would be used as an all purpose cache. Especially when you consider that modern NAND has much lower write endurance than NAND from 3-4 years ago. Modern SSD drives require lots of space in order to fully exploit wear leveling in order to extend the effective life of the drive. At 8 GB, there won't be much you can do about it.
For example, at ~3000 write/erase cycles (typical write/erase endurance of modern MLC NAND) a 120 GB drive will have an average lifespan of ~7.9 years at 50 GB per day of writes. A 250 GB drive on the other hand will last ~15.8 years. It's fairly linear. Move that down to 8 GB and that would be ~0.53 years. Lower it down to 10 GB per day and that goes up to 2.5 years. Still not good enough for a console. You'd want something rated for at least 10 years, IMO. Which would mean 2.5 GB per day of writes. You could easily do that just browsing a flash heavy website (like Youtube) for an hour a day.
Of course, there's things you can do to mitigate that. But that point is that it wouldn't work for a "general" cache. After all, they have to design around the fact that someone, somewhere will use it in the absolute worst case scenario. If you do not do that, then you are just asking for a ton of returns X years from launch. And while that might be out of the warranty period, it won't make many people happy and would greatly tarnish the image of your company.
That just means that it is either going to be a mostly static storage format (like holding the OS) or will feature limited writes (to avoid going over an average of 2.5 GB/day).
So the most likely uses that I can think of for it are...
1) It holds the OS. Simple and makes sure anything OS feature and standard feature are always snappy.
2) It is used to store the contents of memory when in the lowest power state. Standby with memory powered requires a fairly significant amount of power when you are looking at absolute lowest power standby. [specifically referring to the power state where the Xbox One will "drain a fraction of a watt"]
3) It is used to store the most frequently used Apps. These are generally small and hence won't trigger a write/erase cycle whenever a new app is run, unlike a game which would likely trigger a write/erase cycle everytime a game is swapped. Hell, with the size of next gen games, it could likely trigger a write/erase cycle even while running the same game.
Of course, all that goes out the window somewhat if they use older SLC manufactured on a 50 nm or 34 nm process. But that is also quite expensive.
Too bad (as with many other console design aspects) they couldn't have launched in 1-2 years from now. ReRAM instead of NAND would have offered some exciting possibilities. Or even Samsung's upcoming Vertical NAND.
Regards,
SB
liquidboy
Regular
Whilst I agree with you, I would like to highlight that the OS's & HyperV in XB1 is a very very customized reduced subset of big Windows/Server version .. 8GB could be enough for this much reduced OS/HyperV ...
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