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NAND Flash Motivation Becomes Clear

post #1 of 67
Thread Starter 
rather than sticking a NAND flash chip in new computers simply for advanced hibernation capabilities, here's a plausible, additional use for it:

a Virtual Memory Disk (aka "swap drive").

Use of a large NAND flash chip (perhaps up to 4 GB in PowerBooks?) as a complement to the hard disk for virtual memory will provide significant performance improvements over current computers, both mac and pc alike (even pcs that will have the same yonah chips). this new hardware use will further improve apple's cost/benefit rating compared to dells, etc.

pure speculation at this point. what do you think?

-hymie
post #2 of 67


How exactly is that any better than, y'know, just adding more RAM, which would be faster, cheaper and already available? Not to mention lower latencies, being closer to the CPU, ...
post #3 of 67
Thread Starter 
Quote:
Originally posted by Chucker


How exactly is that any better than, y'know, just adding more RAM, which would be faster, cheaper and already available? Not to mention lower latencies, being closer to the CPU, ...


power users with powerbooks already have their RAM maxed out and still have significant use of their hard drive for virtual memory during the day. i think it comes down to real estate inside the computer, not cost (and the cost is falling rapidly anyway, thank you iPod). it will take less room for apple to add a flash chip swap disk than to provide additional RAM slots, while providing the advanced hibernation already speculated and shown off by Intel. I am simply saying this is another potential use for it that will undoubtedly allow for significant performance gains.

flash chips are considerably smaller than RAM chips and have so far made it to at least 16 GB in the labs of some companies, providing plenty of room for upgrades in the future.
post #4 of 67
Quote:
Originally posted by hymie
power users with powerbooks already have their RAM maxed out and still have significant use of their hard drive for virtual memory during the day.

Whawhat now? You could put two 2 GB sticks in a 15- or 17-inch PowerBook. That's 4 GB of RAM. That's the exact capacity you're talking about.

Quote:
it will take less room for apple to add a flash chip swap disk than to provide additional RAM slots

And it'll be less useful, because it will inevitably be further away from the CPU and slower.

It'll be cheaper and provide for higher capacities, but that's about it.

Quote:
flash chips are considerably smaller than RAM chips and have so far made it to at least 16 GB in the labs of some companies, providing plenty of room for upgrades in the future.

Yes, but these kinds of flash chips you're talking about are slower than a hard drive is.
post #5 of 67
Hymie

Chucker is succinctly describing the issue with using Flash in lie of RAM. It simply isn't a performance benefit today. Perhaps in the future but I tend to think that we'll still be using dram chips for the forseeable future.
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post #6 of 67
Thread Starter 
Quote:
Originally posted by Chucker
Whawhat now? You could put two 2 GB sticks in a 15- or 17-inch PowerBook. That's 4 GB of RAM. That's the exact capacity you're talking about.



yes indeed. it is the same capacity i mentioned. however, they are not mutually exclusive as you seem to be implying... they are *complementary*.

therefore, a user with 4 GB RAM and a 4 GB flash disk will thus have - ready - 4 GB RAM and 4 GB for virtual memory if and only if the 4 GB of RAM are fully used.
post #7 of 67
Quote:
Originally posted by hymie
yes indeed. it is the same capacity i mentioned. however, they are not mutually exclusive as you seem to be implying... they are *complementary*.

In theory, they would be. In practice, they cannot be, because your proposed Flash RAM would be significantly slower. It would serve as a backup swap just to prevent crashes, but it wouldn't give any performance boost at all. Quite the contrary.

Quote:
therefore, a user with 4 GB RAM and a 4 GB flash disk will thus have - ready - 4 GB RAM and 4 GB for virtual memory if and only if the 4 GB of RAM are fully used.

A user with 4 GB RAM and 40 GB free disk space (and hard drive space is cheap) can currently have -- ready? -- 4 GB RAM and 40 GB of virtual memory that's faster than what you're proposing.
post #8 of 67
Thread Starter 
Quote:
Originally posted by Chucker
In theory, they would be. In practice, they cannot be, because your proposed Flash RAM would be significantly slower. It would serve as a backup swap just to prevent crashes, but it wouldn't give any performance boost at all. Quite the contrary.



A user with 4 GB RAM and 40 GB free disk space (and hard drive space is cheap) can currently have -- ready? -- 4 GB RAM and 40 GB of virtual memory that's faster than what you're proposing.

nope, wrong again. OS X can use multiple disks for virtual memory. Therefore, this user would have - ready? - 4 GB RAM, 4 GB virtual memory from the flash drive, and an ADDITIONAL 40 GB virtual memory on the hard disk.
post #9 of 67
Quote:
Originally posted by hymie
nope, wrong again. OS X can use multiple disks for virtual memory.

Yes it can. So what?

Quote:
Therefore, this user would have - ready? - 4 GB RAM, 4 GB virtual memory from the flash drive, and an ADDITIONAL 40 GB virtual memory on the hard disk.

You just don't get it, do you? I'll write it out for you again.

FLASH MEMORY IS NOT ONLY SIGNIFICANTLY SLOWER, BUT ALSO MORE EXPENSIVE THAN THE LAPTOP'S BUILT-IN HARD DRIVE.
post #10 of 67
Thread Starter 
Quote:
Originally posted by Chucker
Yes it can. So what?



You just don't get it, do you? I'll write it out for you again.

FLASH MEMORY IS NOT ONLY SIGNIFICANTLY SLOWER, BUT ALSO MORE EXPENSIVE THAN THE LAPTOP'S BUILT-IN HARD DRIVE.


whoa, sorry i missed your brilliance before. if the flash memory is significantly slower than the hard disk in every possible situation, then why is intel marketing this new chip on the motherboard as useful for storing info during deep sleep as opposed to writing everything to the hard disk and then cutting power?
post #11 of 67
Thread Starter 
Quote:
Originally posted by hmurchison
Hymie

Chucker is succinctly describing the issue with using Flash in lie of RAM. It simply isn't a performance benefit today. Perhaps in the future but I tend to think that we'll still be using dram chips for the forseeable future.

hmurchison,
i was in no way stating that the flash would be used in lieu of RAM (nowhere in my original post do I even mention RAM). i was merely stating that it could be used in lieu of the hard disk for some amount of virtual memory. the "virtual" part of virtual memory implies a *separate* method than physical RAM (or the dram you mention) for memory storage, which historically has been the hard disk. the flash drive would be completely compatible with continuing to use the RAM as RAM and the hard drive as virtual memory, but would complement the hard disk virtual memory and could be used to offload tasks as needed from a heavily used hard disk.
post #12 of 67
Everyone is aware that RAM is volatile and NAND is persistent, right? Just making sure.
post #13 of 67
Quote:
Originally posted by hymie
whoa, sorry i missed your brilliance before. if the flash memory is significantly slower than the hard disk in every possible situation, then why is intel marketing this new chip on the motherboard as useful for storing info during deep sleep as opposed to writing everything to the hard disk and then cutting power?

Maybe because Intel manufactures this little chip and not the hard drives???
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post #14 of 67
Quote:
Originally posted by hymie
hmurchison,
i was in no way stating that the flash would be used in lieu of RAM (nowhere in my original post do I even mention RAM). i was merely stating that it could be used in lieu of the hard disk for some amount of virtual memory. the "virtual" part of virtual memory implies a *separate* method than physical RAM (or the dram you mention) for memory storage, which historically has been the hard disk. the flash drive would be completely compatible with continuing to use the RAM as RAM and the hard drive as virtual memory, but would complement the hard disk virtual memory and could be used to offload tasks as needed from a heavily used hard disk.

This is technologically beyond the ability of modern OSes. It's technologically possible in some future OS, but dynamically deciding where to write an OS data file depending on resource load is an exceptionally hard thing to get right, especially when the load ratios are allowed to change. Or another problem is what do you do when the flash swap area runs out of space? Not a minor question when you deal with large data sets in a 64-bit address space. You can always hook up a bigger disk, but you can't just solder in more flash.

So that leaves one statically determined partition as the place the OS swap file will call home. Not to mention HD's with onboard RAM caches are faster than current NAND Flash arrays.

To make the case for a change as major as you advocate, engineers are going to want an immediate and sustainable advantage of greater than 2X faster for the completely new tech, or a near-guarantee the current tech will fall even farther behind that new tech in the next 3-5 years despite the new tech not being faster today. Overall, the risk-reward ratio of your idea isn't great.
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post #15 of 67
Thread Starter 
Quote:
Originally posted by Hiro
This is technologically beyond the ability of modern OSes. It's technologically possible in some future OS, but dynamically deciding where to write an OS data file depending on resource load is an exceptionally hard thing to get right, especially when the load ratios are allowed to change. Or another problem is what do you do when the flash swap area runs out of space? Not a minor question when you deal with large data sets in a 64-bit address space. You can always hook up a bigger disk, but you can't just solder in more flash.

So that leaves one statically determined partition as the place the OS swap file will call home. Not to mention HD's with onboard RAM caches are faster than current NAND Flash arrays.

To make the case for a change as major as you advocate, engineers are going to want an immediate and sustainable advantage of greater than 2X faster for the completely new tech, or a near-guarantee the current tech will fall even farther behind that new tech in the next 3-5 years despite the new tech not being faster today. Overall, the risk-reward ratio of your idea isn't great.

thank you for a detailed and cogent response. However, I disagree with you on the technological feasibility of this item. For years, Adobe Photoshop has allowed you to enable multiple swap partitions to be used, and to specify their order of use (e.g. when the first swap disk is full, move to the second one, etc.). If photoshop can do it, i see no reason why OS X cannot do it as well. Is there something else I am missing?
post #16 of 67
Quote:
Originally posted by hymie
whoa, sorry i missed your brilliance before. if the flash memory is significantly slower than the hard disk in every possible situation, then why is intel marketing this new chip on the motherboard as useful for storing info during deep sleep as opposed to writing everything to the hard disk and then cutting power?

I believe it has something to do with spin up/spin down. Hard disks take longer to get going than flash (a couple of secs), during which time they are slower. It is also advantageous to avoid spinning up the hard disk more often than necessary to preserve its lifespan, and it is probably desirable when putting a computer into sleep mode if its hard drive doesn't continue to whirr for several minutes as you manhandle it into your rucksack, risking damage to the drive, and potentially upsetting airport baggage inspectors, who generally don't like it if bags make funny noises.

Power consumption may also be a factor - if you've put your machine to sleep it may be because the battery is nearly flat, in which case it would be preferable if the process of spinning up the hard disk to preserve its memory to permanent storage did not cause the battery to run out before it finishes backing up.

I'm pretty sure it is not because flash is faster than a hard disk.

I suppose however, although I am no engineer, that there might be merit to your scheme if the flash cache (hey, that rhymes) allowed the hard drive to remain asleep for longer while the machine is awake, thereby preserving its lifespan, and your battery life, and keeping your computer quieter.

I can already see several possible flaws though. If it is as significant as has been claimed, then the speed differential probably makes the issue moot (you certainly don't want your virtual memory to be any slower than necessary). I have also heard it suggested on these forums that the lifespan of flash under heavy read/write usage is not favorable compared to hard disks, in which case it would be foolish to sacrifice the lifespan of a fairly expensive flash chip to save a comparatively cheap hard drive.

But then on the third hand, your hard disk has all your important stuff on it, and I'd rather pay to replace a dead flash chip than to have my vital documents recovered bit-by-bit from a dead hard drive.
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post #17 of 67
It occurs to me that using flash as swap space has no benefit over using old,slow ram. It's probably faster than flash, and perhaps even cheaper.

Presumably sufficiently slow ram is reasonably cheap - the only reason why modern ram is so expensive is that it has to be fast.

There is no reason why a ram cache would need to be persistent - the only reason why the hard disk is used is because it's the only available storage when the ram runs out, not because the permanency of it offers any advantage (which is what lanky_nathan was getting at, I expect).

So why don't modern laptops come with oodles of old, crap ram in addition to half a gig or so of speedy ddr stuff? It wouldn't need to be upgradeable, so they could just stick a few gig of it straight on the motherboard, which shouldn't take up much space.

My guess is that the answer to that is the same as the answer to the question of why flash isn't used for this purpose.
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post #18 of 67
Quote:
Originally posted by hymie
whoa, sorry i missed your brilliance before. if the flash memory is significantly slower than the hard disk in every possible situation, then why is intel marketing this new chip on the motherboard as useful for storing info during deep sleep as opposed to writing everything to the hard disk and then cutting power?

Because there is a small period of time that the cpu could be starting (aka spinning-up) the HD, and reading from the Flash drive, and then it can read from the HD. But during that period the CPU could be reading from the Flash memory. It also could be used to add to the band width of the HD, so that large files like parts of the OS and Applications would be pulled from the HD while things like where you were at in a file could be stored on the Flash drive. Now in theory this could be used as an auto save to a Jump drive as well, but the experience could also be an almost instant on. So there is latency issues, but frequently this is over come with band width. So a chip is slow, but what if they are stacked wide instead of deep. Or interlacing them.
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post #19 of 67
Thread Starter 
well, so much for that discussion... it IS coming for virtual ram capabilities, but it looks like more for battery performance than overall speed. guess i didn't need to speculate after all: Linky link link

Interesting that some manufacturers (read: Samsung) will be adding it directly to hard drives, too (128 MB)!

Quote:
Both Samsung and Intel have been working on ways of hybridizing flash memory and hard drives, while Microsoft is expected to offer SuperFetcha feature that can take advantage of flash memory to boost system performanceas part of its Windows Vista operating system. Vista is due in the fall of 2006.

......

"On startup, you retrieve information from the nonvolatile memory [flash] instead of the hard drivethis is fasterthen, during the operation of the PC, write to nonvolatile memory and don't spin the disk and save battery life," said Mike Graf, a manager for mobile platform strategy inside Intel's Mobile Platforms Group.

Although Robson will work in any type of PC and with several operating systems, including Windows and Linux, Intel believes its ability to reduce boot times and boost battery life offers the greatest benefits to notebooks. Thus the company is targeting the portable PCs first, Graf said.
post #20 of 67
Quote:
Originally posted by hymie
whoa, sorry i missed your brilliance before. if the flash memory is significantly slower than the hard disk in every possible situation, then why is intel marketing this new chip on the motherboard as useful for storing info during deep sleep as opposed to writing everything to the hard disk and then cutting power?

Because flash memory still has better latency than hard drives.
post #21 of 67
This sounds like a solution in search of a problem. When I open the lid on my PB by the time I lift it up and type in my password the hard drive is spinning full speed.
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post #22 of 67
wow, all i can add is: "Hennessy and Patterson"
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post #23 of 67
That went so far over some heads heads here as to not be visible. Right along with Stallings or Tanenbaum & Woodhull or Silberschatz, Galvin & Gagne.
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post #24 of 67
Yeah, well... Morecombe & Wise, Little & Large, Skinner & Badiel, The Two Ronnies.. do I need to go on?
post #25 of 67
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post #26 of 67
Reading from flash memory will be faster than reading from a hard disk -- especially one that you need to spin up and seek. It also draws enormously less power. There are plenty of things in the OS only rarely (e.g. the code), and storing those in a flash memory disk would be very beneficial. If the OS designers are really on the ball they can probably identify the state that needs to be preserved and write that to the flash disk when going to sleep, ignoring all of the state which is just about to be tossed away anyhow (i.e. empty buffers and such).
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post #27 of 67
But that's not a usage case for swap, since swap relies on writing just as much as on reading.
post #28 of 67
Quote:
Originally posted by Programmer
Reading from flash memory will be faster than reading from a hard disk -- especially one that you need to spin up and seek. It also draws enormously less power. There are plenty of things in the OS only rarely (e.g. the code), and storing those in a flash memory disk would be very beneficial. If the OS designers are really on the ball they can probably identify the state that needs to be preserved and write that to the flash disk when going to sleep, ignoring all of the state which is just about to be tossed away anyhow (i.e. empty buffers and such).

hymie originally proposed using flash memory as a second hard drive exclusively for swap. It doesn't make any sense, frankly speaking, for 2 reasons: cost and... cost. It would add at least a hundred bucks per machine, while for the same money you can just get a hard drive of maximum capacity available. And it would not require any engineering effort.

Of course, we all want flash memory drives instead of bulky spinning hot noise generators, but while those are dirt-cheap compared to NAND, I'm afraid we have to wait. Personally, I'm scared to think about the price of a 150GB flash drive (if you want to fall off your chair, look here).

What Programmer is talking about is a whole different story, but in essence the same thing. For deep/safe sleep or whatever they call it the idea is to save RAM content somewhere on sleep and restore it on wake-up. A hard drive is perfectly suitable for this purpose. Who cares if the process takes a couple of seconds less if the cost is extra $100-$200? Moreover, if flash memory price decrease continues as a trend at its current rate, in 3 or 4 years we will use flash memory everywhere.
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post #29 of 67
Quote:
Originally posted by costique
hymie originally proposed using flash memory as a second hard drive exclusively for swap. It doesn't make any sense, frankly speaking, for 2 reasons: cost and... cost. It would add at least a hundred bucks per machine, while for the same money you can just get a hard drive of maximum capacity available. And it would not require any engineering effort.

Of course, we all want flash memory drives instead of bulky spinning hot noise generators, but while those are dirt-cheap compared to NAND, I'm afraid we have to wait. Personally, I'm scared to think about the price of a 150GB flash drive (if you want to fall off your chair, look here).

What Programmer is talking about is a whole different story, but in essence the same thing. For deep/safe sleep or whatever they call it the idea is to save RAM content somewhere on sleep and restore it on wake-up. A hard drive is perfectly suitable for this purpose. Who cares if the process takes a couple of seconds less if the cost is extra $100-$200? Moreover, if flash memory price decrease continues as a trend at its current rate, in 3 or 4 years we will use flash memory everywhere.

Everyone says the same thing, so what about those two seconds, but I notice that my internet connection takes awhile to return from sleep, as well as mail that depends on that connection. If even these things were stored on flash then they would wake-up faster. The cost is related to the size of the module, like the size of LCD screens, you could buy 3+ 20" LCDs from Apple for the cost of one 30"LCD. The point is that 256MB is cheap and stacked they are economical, I also believe that there could be a way to interleave them to offset some of the latency issues. Like a controller could be pulling from two banks of 256MB that are both interleaved. Instead of buying one 1Gig flash module, 4x256MB are stacked.
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post #30 of 67
Quote:
nd it is probably desirable when putting a computer into sleep mode if its hard drive doesn't continue to whirr for several minutes as you manhandle it into your rucksack

My PC laptop with 1 GB of memory takes less that 10 seconds to hibernate to disk and same time to come back to life. Not "several minutes" as you say.
And I don't usually "manhandle" my laptop at any time and I would not recommend manhandling the laptop to anyone regardless whether it uses hard disk or flash.

I could see an advantage in some cases if you can make hybernation instant (like standby mode), but I don't see how that is possible with flash RAM speed these days.

Quote:
This is technologically beyond the ability of modern OSes. It's technologically possible in some future OS, but dynamically deciding where to write an OS data file depending on resource load is an exceptionally hard thing to get right, especially when the load ratios are allowed to change.

Why is that? It's been done for years in the micro-code for processors with exteremely high efficiency. That's how branch prediction and cache management works, my friend.
In fact you don't even need a new OS for it. Just a low level memory management driver. Similar software exists for Windows 2k/XP, for example. It's called Ramdisk.
You can do it, but in order for this to be beneficial compared to just writing to RAM, in terms of speed, you Flash memory will need to have comparable transfer speed.
post #31 of 67
Quote:
Originally posted by skatman
Why is that? It's been done for years in the micro-code for processors with exteremely high efficiency. That's how branch prediction and cache management works, my friend.
In fact you don't even need a new OS for it. Just a low level memory management driver. Similar software exists for Windows 2k/XP, for example. It's called Ramdisk.
You can do it, but in order for this to be beneficial compared to just writing to RAM, in terms of speed, you Flash memory will need to have comparable transfer speed.

You are confusing the operations of custom built embedded processors running in a defined sandbox of an application space and a generalized operating system where folks have proposed writing state bytes willy nilly to different devices dependent on bandwidth load to the devices.

Big difference. Read what they want again, it's not a single device RAMDisk, they want realtime interleaving of devices swap space, and not in a RAID style either -- that interleaving is statically determined.

There has been a side discussion on NAND as a replacement for power-off persistent storage in sleep. A completely different issue and only a matter of $$, not tech.
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post #32 of 67
Quote:
Originally posted by Hiro
You are confusing the operations of custom built embedded processors running in a defined sandbox of an application space and a generalized operating system where folks have proposed writing state bytes willy nilly to different devices dependent on bandwidth load to the devices.

Not really. These types of dynamic load/ prefetch/ brandch prediction mechanisms are standard in the microcode of any processor ranging from G5 in MAC to Intel Pentium 4.
Perhaps a review of micro-architecture of modern processors is in order here. May I suggest "Computer Organization and Design" by David Patterson and John Hennessy?! It's a bit heavy on formal logic and math at times, but still inetresting if you really want to know how it works in detail.
But even in the case where this is implemented, I don't see an advantage unless Flash is made MUCH faster than HD.
post #33 of 67
Someone's late to the party, count up about 11 posts.

The existence of dynamic load/ prefetch/ brandch prediction mechanisms on a CPU don't magically make really hard things simple. As you said just about every CPU today has them, if it made those kind of dynamic things trivially easy AI wouldn't be the shambles it currently is, filesystems would grow on something other than B-trees and Santa Claus would bring me a Lego X-Wing Collectors Edition for Xmas.
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post #34 of 67
If my memory serves me correct, Flash memory has a limitation regarding the number of write-operations you can do on Flash. I think there is a barrier at about 1000 write operations. Above that number the Flash memory is more and more likely to fail.

copland
post #35 of 67
I couldn't help from chiming in again with respect to some of the flash rumours. The little bit I've heard about the use of FLASH with respect to Intels research is using the technology as a CACHE for a HARDDISK. The intent is to lower the amount of energy used to spin up a disk which is extremely significant in a laptop.

The idea has merit and if done in such a way that only read only code is cached may be compatible with write limitations that flash has. The write limitations are real but with todays technology much higher than suggested by some here. Further such an array would likely be protected by some sort of error detection and correction. The possibility of bits flipping is real and would have to be protected against.

As to speed, flash used in such a way would be many times faster than a harddisk. Not just one or two times either, but likely hundreds of times faster over a disk that is asleep. All of this while using significantly less power. that of course is read times, writes are another thing where I would imagine all data would be sent directly to the harddisk.

There are a number of reasons why I would suspect that the cache would be designed to cache only executeable code. The primary one being the reality that data could easily flush such a cache resulting in a loss of its intended functionality.

Finally I don't see this idea being an Apple exclusive. Apple will have a very hard time differentiating its hardware relative to the windows suppliers. I'd suggest that they will focus on software and possibly hardware accelerators. The thing is the hardware would have to be Apple exclusive to mean anything. So I don't expect to see to much focus on this technology at all other than its newness.


Thanks
Dave
post #36 of 67
Quote:
Originally posted by copeland
If my memory serves me correct, Flash memory has a limitation regarding the number of write-operations you can do on Flash. I think there is a barrier at about 1000 write operations...

The number was 100,000, not 1,000, and I don't think that has been a problem for some time.
post #37 of 67
you're thinking about flash memory from 2-3 years ago. This is advanced flash memory that intel is pushing, it's not the memory that comes in those memorysticks you buy in the stores, or on your ipod. It's much faster. Think solid state ram.


Quote:
Originally posted by hymie
whoa, sorry i missed your brilliance before. if the flash memory is significantly slower than the hard disk in every possible situation, then why is intel marketing this new chip on the motherboard as useful for storing info during deep sleep as opposed to writing everything to the hard disk and then cutting power?
post #38 of 67
actually current ram, say take a nand ram has 11million write cycles pre bit on the disk. If you were to write to them all nonstop starting today, it would take over 90 years of nonstop abuse for it to "possible be able to" fail.

Try that with your hard drive.


Quote:
Originally posted by copeland
If my memory serves me correct, Flash memory has a limitation regarding the number of write-operations you can do on Flash. I think there is a barrier at about 1000 write operations. Above that number the Flash memory is more and more likely to fail.

copland
post #39 of 67
Quote:
Originally posted by webmail
actually current ram, say take a nand ram has 11million write cycles pre bit on the disk. If you were to write to them all nonstop starting today, it would take over 90 years of nonstop abuse for it to "possible be able to" fail.

I don't follow your logic here. Current write speeds appear (from a Google search) to be in the 100-500 usec range which implies that you could achieve at least a thousand write cycles per second and burn out your flash memory in less than half a week, if you really tried. And 1-5 million cycles is more typical. Certainly well short of "90 years of nonstop abuse".

Nonetheless, flash memory has certainly improved and use as a disk replacement is entirely viable... except in terms of cost. Small disks for key items that you want rapid & frequent access to make a lot of sense though, and that is why we're seeing the news items. I wouldn't be surprised if desktop and notebook machines start coming with 0.5-2 GB of Flash memory which the OS uses for its own backing store and other key files. Low power, fast access (relative to disks), high reliability, rapid on time, etc.

Read cycles appear to be sub-100 ns too, which is pretty blazingly fast. Faster than I had thought. Flash disks with 20-50 MB/sec sustained read rates are currently available, and I imagine that putting more chips in one device can increase that by reading in parallel (you can usually increase bandwidth that way, unfortunately there is no equivalent for latency reduction). Definitely not RAM-replacement speeds (1000x too slow) but in the realm of disk speeds.
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post #40 of 67
Quote:
Originally posted by webmail
Think solid state ram.

All RAM is solid state (well, at least since the days of core memory... and I don't know if you could call that solid state or not as it had no moving parts). The older flash memory technologies and EEPROM are solid state too. You're better off just saying "technology has improved, forget what you knew about flash memory".
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