Phase Change Memory vs. Storage As We Know It 130
storagedude writes "Access to data isn't keeping pace with advances in CPU and memory, creating an I/O bottleneck that threatens to make data storage irrelevant. The author sees phase change memory as a technology that could unseat storage networks. From the article: 'While years away, PCM has the potential to move data storage and storage networks from the center of data centers to the periphery. I/O would only have to be conducted at the start and end of the day, with data parked in memory while applications are running. In short, disk becomes the new tape."
Re:CD-R? (Score:5, Insightful)
Phase change memory is nothing like A CD-R. This stuff has the density of a hard drive, and the speed is very close to DRAM. It's non-volatile to boot. It's a serious contender to become universal memory.
Imagine how different operating systems and programs would be if we could make RAM non-volatile.
Re:CD-R? (Score:3, Insightful)
"Imagine how different operating systems and programs would be if we could make RAM non-volatile."
Pretty much like they are now? Does anyone actually cold boot their machines anymore?
Now, if RAM were as cheap as hard disks....
Why the vapourware tag? (Score:5, Insightful)
How soon we forget. The article is speculative, sure, but the hardware is not only real, it's in mass production by Samsung: http://hardware.slashdot.org/article.pl?sid=09/09/28/1959212 [slashdot.org]
Just looking at the numbers, the article is a bit overblown. Phase change memory will first be a good replacement for flash memory, not DRAM. It's still considerably slower than DRAM. But it eliminates the erasable-by-page-only problem that has plagued SSDs, especially Intel SSDs, and the article does mention SSDs as a bright spot in the storage landscape. PCM should make serious inroads into SSDs very quickly because manufacturers can eliminate a whole blob of difficult code. With Samsung's manufacturing muscle behind it, prices per megabyte should be reasonable right out of the gate and as Samsung gets better at it, prices should plummet even faster than flash memory did.
The I/O path between storage and the CPU will get an upgrade, and it could very well be driven by PCM. Flash memory SSDs are already very fast and PCM is claimed to be 4X faster. That saturates the existing I/O paths (barring 16-lane PCIe cards sitting next to the video card in an identical slot). Magnetic hard drives haven't come anywhere close to saturation. Development concentrated for a decade (or two?) on increasing capacity, for which we are thankful, but the successes in capacity development have outrun improvements in I/O speed. In turn, that meant that video cards were the driver behind I/O development, not storage. Now that there's a storage tech in the same throughput class as a video card, I expect there to be a great deal of I/O standards development to deal with it.
But hard drives == tape? Not for a long long time. The development concentration on increasing capacity will pay off for many years to come. PCM arrays with capacities matching modern hard drives (2 TB in a 3.5" half height case. Unreal!) are undoubtedly a long ways off.
Hopefully there are no lurking patent trolls under the PCM bridge...
Re:CD-R? (Score:3, Insightful)
The speed of PCM would need to closely match - or exceed - the speed of DRAM for people to adopt it as a replacement, so I doubt the model would quite be one of non-volatile RAM. I imagine it would be more like having a ridiculously fast SSD.
Given the propensity of programs to corrupt and/or leak memory, I'm not sure I'd want my system memory to be non-volatile. The dividing line between system memory and mass storage allows for robustness against errors which, without the ability to reboot, wipe the slate clean and load up the last saved data, might end up being catastrophic. It'd be nice if no program ever had such errors, but this is reality. ;)
If nothing else, programs will always need the ability to serialise data into platform-agnostic formats, unless you expect the world to standardise on one platform or stop sharing data.
This "author' is pretty much irrelevant (Score:5, Insightful)
I was tempted to stop reading right there, but I kept reading. While his point about POSIX improvements is not bad, the rest of the article is ridiculous. It essentially amounts to: Imagine if we had pretty much exactly what we have today, but we used different words to describe the components of the system! We already have slower external storage (Networked drives / SANs, local hard disk), and incremental means of making data available locally more quickly by degrees (Local Memory, L2 Cache, L1 Cache, etc.) We already get that at the expense of its ability to be accessed by other CPUs a further distance away. It turns out I probably should have stopped reading when I first got the feeling I should when reading the first sentence in the article: "Data storage has become the weak link in enterprise applications, and without a concerted effort on the part of storage vendors, the technology is in danger of becoming irrelevant." I can't wait to answer with that one next time and watch jaws drop:
...
Boss: Where and how are we storing our database, how are do we ensure database availability, and how are we handling backups?
me: You're behind the times Boss. That is now irrelevant!
Yeah. That's the ticket
Re:Why the vapourware tag? (Score:2, Insightful)
The only thing plaguing Intel SSDs is price. And I don't think that particular aspect makes Intel real sad.
Re:CD-R? (Score:0, Insightful)
Not really (Score:5, Insightful)
First off most non-volatile RAM isn't nearly as fast as DRAM. So let's assume you mean "what if everything were in DRAM, and that was non-volatile, it would be so much faster". Well, again not really. Faster, but there are far more bottlenecks than just disk I/O. You can go buy ramdisks now, or you could make them in your current RAM, copy the OS there, and run off that after you boot. Go try it. Firefox isn't going to render quicker, your mail isn't going to load any faster, and youtube isn't going to lag any less. If you work with large photos, most software is already going to exhaust your RAM, so (given you have sufficient quantities) you're already not losing anything.
In short, because of modern hard disk and OS caching, the ridiculous quantities of RAM these days, and a current reliance on the network for most tasks, a pure ramdisk system isn't likely to be that much better for most people. If you put a large database or maybe compile there, you would see improvement. But that's not common for most people.
Re:Why the vapourware tag? (Score:3, Insightful)
Kevin has this right, what an obtuse article.
Henry Newman is talking about PC storage not enterprise storage. He discusses all disk IO performance in MBs/sec, meaning sequential. When in reality, very little (disk level) IO for the enterprise is sequential. The numbers here are flawed as is the characterization of storage.
Storage is where we keep our data. Keeping data is a central requirement of information technology. It will never be a peripheral feature.
Presently the real IO bottleneck is the spinning platter and the requirements of getting a read/write head to the right place quickly. Newer solid state storage devices will alleviate this bottleneck in the very near future. Perhaps PCM is the solution, but I for one will wait for a GB/$ threshold at which time the winning solid state storage will be available to everyone.
Mr. Newman talks about inter-computer bus speeds as not keeping up with CPUs and memory, when in fact they keeping up. The place where data transport still can't keep up, is serially on a single transport, (wire or optical). Networked (switchable) data needs to be serial single transport for a number of obvious reasons. Like the platter, this is a physical limitation and not easily surmounted.
If and when we get +10GB/sec consumer networks, storage networks (transporting SCSI blocks) will become a thing of the past as we pass and store all our data in an application aware protocol.
Re:We're almost there already (Score:3, Insightful)
Re:We've heard this forever... (Score:3, Insightful)
Despite what the article writer thinks, if PCM is that great, the storage manufacturers will just create storage devices that use PCM technology. The other option is to go out of business
I see lots of "normal" people using external storage drives. These people are far less likely to open up their computer and swap chips on their motherboard.
Transferring 1TB from my house to my office by hand is faster and more reliable than using my crappy ISP. If the writer thinks storage IO speeds are bad, he should look at the internet speeds in many parts of the world.
Having your storage on a "drive" makes it easier to upgrade (or even hot-swap), than having it on the motherboard.
Motherboards that allow you to hot swap memory or CPUs tend to be expensive.
Also, stuff that plugs into one motherboard can't always be plugged into next year's new technology motherboard.
Trust me, being able to read the same drive on a totally different computer is something very important.
By the time you've designed a suitable interface, storage format, protocols and physical connectors for all of that, the stuff that plugs into it might as well be called a drive.
And whatever you call it, the storage companies will be building it.
FWIW, I do hope that storage I/O speeds increase dramatically, and very soon. It's already 2010, progress has been rather slow IMO