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Phase Change Memory Points To Future of Storage
An anonymous reader writes
"A UC San Diego team is about to demonstrate a solid state storage device that it says provides performance thousands of times faster than a conventional hard drive and up to seven times faster than current state-of-the-art solid-state drives. The drive uses first-of-its-kind phase-change memory, which stores data in the crystal structure of a metal alloy called a chalcogenide. To store data, the PCM chips switch the alloy between a crystalline and amorphous state based on the application of heat through an electrical current. To read the data, the chips use a smaller current to determine which state the chalcogenide is in."
My very first reaction was to think of Asimov's Foundation trilogy and the fact the the Galactic Library was stored as nicked quanta in a paperweight on the Librarian's desk. The Barbarians allowed him to take his personal belongings with him before they destroyed the Library Planet.
No longer will I need a huge magnet, now I just need a hair dryer!
But Seriously, wouldn't external heat sources pose a problem for such a technology? I don't want my drive erased next time my electricity goes out during the summer.
Where genius and insanity become confused true wisdom is found
To store data, the PCM chips switch the alloy between a crystalline and amorphous state based on the application of heat through an electrical current.
That seems like probably not a very good idea, and I'm sure it will end up being one of the major hurdles to this technology really getting off the ground. What happens when the memory is heavily used (leading to buildups of heat in the memory that could cause unintentional bit changes)? Obviously the heat used to flip the bits must be dissipated very, very quickly, and that's a pretty challenging problem in its own right. Also, what happens to system temps when you use this memory? Many systems are already difficult to keep cooled, and adding another source of heat could be a particularly bad idea. Heck, what if the increase in system temps leads to memory faults? After looking over the Wiki, the last question seems unlikely to be a problem, but heating something to >600C seems like it could make it very hard to use this tech in heavy use situations.
skimmed some papers on PCM on the web, looks like their goals are to get the memory to 100 million writes and 10 years retention of data; very similar issues to flash, it seems
So, what's up with the name of the system, "moneta", is it what I think it is (a Russian word for 'coin'), or is there something else at play here? I am a bit confused, because in the article, (which I am sorry to admit I read), it mentioned a bunch of names, but none that were Russian sounding.
You can't handle the truth.
I actually skimmed the article and I didn't see any mention of data density. Anyone know how it compares?
Vote monkeys into Congress. They are cheaper and more trustworthy.
Phase change memory tech is not new as most readers here will know. Nearly all the major semiconductor companies have worked on prototype versions of this tech. If companies like Samsung and Intel haven't succeeded in mass producing it yet, as a consumer I'd be more interested in knowing what sets this particular device apart from all the others that will make it more likely to reach the market for the masses. Cheaper to produce? Scales more easily? More energy efficient? More stable?
"The only normal people are the ones you don't know very well."
Is what is the number of cycles before a given bit can no longer be changed. Will this outlast the current SSD write cycle limitations that are getting smaller not longer with the ever shrinking die size thus resulting in having to have 2x or 4x the actual advertised RAM installed to meet ever increasing MTBF rates..
Beware the Lollipop of Mediocrity, Lick it once and you suck forever.
If it works as described with the PCB generating heat to change the substance from a crystal to a liquid, once that heat is removed via loss of power, all would change back to a crystal, and you would lose all your data. This may be fine for RAM, but not for storage.
We were all warned a long time ago that MS products sucked, remember the Magic 8 Ball said, "Outlook not so good"
A UC San Diego team is about to demonstrate a solid state storage device that it says provides performance thousands of times faster than a conventional hard drive and up to seven times faster than current state-of-the-art solid-state drives.
I don't know why, but the speed comparisons in the summary amuse me. "This is THOUSANDS of times faster than a conventional hard drive — absolutely phenomenal speed gains, faster than anything else ever seen in the conventional hard drive world , speeds which will blow your mind straight out of your skull with how much blindingly faster they are than conventional hard drives, literally THOUSANDS of times faster — and kinda sorta faster than solid-state drives."
Demanding constant attention will only lead to attention.
I had a PDA with NVRAM and I never noticed it getting more than slightly warm - and if the memory did get significantly hot, it would have drained the battery very fast.
"When information is power, privacy is freedom" - Jah-Wren Ryel
If it works as described with the PCB generating heat to change the substance from a crystal to a liquid, once that heat is removed via loss of power, all would change back to a crystal, and you would lose all your data. This may be fine for RAM, but not for storage.
Actually I think you'll find it's the same material and a similar principle to CD-RW disks. The difference is that in CD-RW they are heating it with a laser, and reading it back optically. In PC memory, they are probably heating it electrically, and they are using a change in resistance rather than a change in reflectivity to read it back.
Hardly skunkworks. PCM chips are in Micron's (Numonyx) catalog. I considered using one in a design last year, but they were too expensive, mainly because I only needed a wee bit of non-volatile storage and these chips only come in 128 Mbit density.
You can buy them from Digikey at $4.57 each. But you have to buy them a tray at a time (576 parts per tray).
I'm struggling to understand what these researchers have made, exactly. They certainly didn't invent phase-change memory, and the article states that this "Moneta" uses memory modules from Micron Technology. The wikipedia article mentions Samsung started shipping modules last year, ready for use in mobile applications. So clearly PCM has been available for some time. So perhaps Moneta is an actual device available for end users? That would be exciting!
So it's not ready then. I really cannot see what these guys have achieved.
"A week in the lab saves an hour in the library"
Make that 8.8 gigabits per second compared to 6Gb/s hard drive. Doesn't sound revolutionary. There must be something in the other details that make this exciting.
The only way for the speed comparison to make sense so that we get a 1000x improvement on conventional harddisks and only a 7x improvement on flash is if speed is referring to latency instead of bandwidth, which is correct even if counter to normal marketing material. If the stated bandwidth is for a small element then you can add X of those elements to your drive to multiply the bandwidth by X, so possibly the bandwidth could be pretty good too.
No. Power is needed for the phase change (flipping a bit). PCRAM is non-volatile - it does not require power to retain its state. That's the entire point...
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"switch the alloy between a crystalline and amorphous state"
Interesting, this is similar how cd/dvd-rw works, where they use a laser to do the state change.
It's not switching between solid and liquid. It's switching between crystaline and amorphous solid (stated in the first wikipedia intro, second link in the article). It takes a small amount of heat to make it switch between the two states, and they have different properties that can be measured, but both states are static in the absence of heat. What you described would make no sense at all, since if the PCB knows to provide heat to certain places then it already has external memory.
Of more interest is the security of the data stored in PCM. Can you erase it by putting it in a microwave? Leaving it in a hot car? Will it be easy to make a microwave beam/laser to erase parts of the drive from outside? The answer is probably no, but it will be very interesting to see the temperature specs on the resulting consumer products.
OUM/OVM memory for storage applications. The IOPS should be quite nice once done properly.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
Why thank you for this incredibly useful comment!
For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
see: http://www.physorg.com/news/2011-05-samsung-mass-30nm-class-gigabyte-memory.html
Samsung has had 32GB/40nm sticks out for over a year, 16GB out for 2 years, now they are about to ship the 30nm 16/32GB modules with lower power consumption. Price per GB is bad.
Memory4less has:
Samsung 16GB PC3-8500 DDR3-1066MHz ECC Registered CL7 240-Pin DIMM
~$950, other speeds for more $
32GB sticks run ~$2,150 and up
= about 6 to 7 times the cost/GB of vanilla 4GB sticks on newegg, or about 3 to 4 times the cost/GB of 8GB ECC sticks.
"Is life so dear, or peace so sweet, as to be purchased at the price of chains and slavery?" - Patrick Henry