'Racetrack' Memory Could Replace Hard Drives?

Galactic_grub writes "An experimental new type of memory that uses nanosecond pulses of electric current to push magnetic regions along a wire could dramatically boost the capacity, speed and reliability of storage devices. Magnetic domains are moved along a wire by pulses of polarized current, and their location is read by fixed sensors arranged along the wire. Previous experiments have been disappointing, but now researchers have found that super-fast pulses of electricity prevent the domains from being obstructed by imperfections in the crystal."

I've seen it in fibre before...

[simm1701 (835424)]

I remember reading some research a couple of years ago that somethign similar was done using 100km of optical fibre and a router programmed to keep sending the same stuff around the loop, or it could read it/write it as it came around.

In some ways being slower is definitely an advantage, even with 100km at 10Gb/s you don't have much storage when the bits are moving at the speed of light.

Re:I've seen it in fibre before...

[kaszeta (322161)]

I remember reading some research a couple of years ago that somethign similar was done using 100km of optical fibre and a router programmed to keep sending the same stuff around the loop, or it could read it/write it as it came around.

The basic technique is even older than that. Google "Mercury Delay Line" for early examples: they'd make a long thin tube of mercury with transponders at each ender. It was around 5 ft per K, IIRC.

Re:I've seen it in fibre before...

[by Anonymous Coward]

Mercury delay lines were the cause of a bizarre
computer architecture. The normal form of instructions
had an "address of next instruction" field.

After getting the program to "work", i.e get the correct
answer, the "optimization" stage consisted of working out how
long each instruction would take, and then positioning the "logically next"
instruction at the location just about to appear out of the delay line.

There was no advantage to inner loops that were faster than the
delay round the mercury loop. Unless you could unroll and fit two
repetitions into one trip round.

Of course, all of this was done by hand.

Plus one addressing

[A nonymous Coward (7548)]

Generally known as n + 1 addressing, where n was how many operands had addresses in the instruction. Also used with drum memory, which was in the physical shape of a cylinder ion the one drum machine I used, but was mainly a head per track disk, so no seeking required. Some drums had multiple heads per track for some tracks to reduce latency further.

The optimization was great fun, my favorite part. You could make programs scream if you paid attention.

Re:Plus one addressing

[Rorschach1 (174480)]

Mel [pbm.com]? Is that you?

Re:

[by Anonymous Coward]

if I had a dollar for every time they've said "this new XYZ technology could replace hard drives," I could buy a lot of hard drives

Re:

[simm1701 (835424)]

Sounds like an idea for a slashdot poll:

Which is your favorite vapourware "hard disk replacement"? :)

Re:

[simm1701 (835424)]

Not really...

10Gbps = 1.25GB/s
c = 300,000Km/s (2sf)

Does 100km in 1/3s

1.25GB/s * 1/3 s = 0.416GB

I think your answer is off by a factor of 1000 (or maybe 1024) :)

This sounds....

[Dogtanian (588974)]

...vaguely reminiscent of "Bubble Memory" 25 years ago. And everyone was saying *that* was going to replace hard drives too.

Anything

[eldavojohn (898314)]

Anything would be better than the current way my hard drive works. Spinning discs on a platter?! A thousand moving parts?! What is this, the Stone Age?!

Re:Anything

[Silver Sloth (770927)]

Anything would be better than the current way my hard drive works

You mean a technology that is

• cheap
• reliable - OK, hard drive errors do exist but I wish my car, for example, was as reliable
• standardized - OK, there are a number of standards but not that many

Yes, in the long term I don't see the hard drive as the best method of data storage but the altenatives have a long way to go before they replace it.

Hard disks vs Cars

[giafly (926567)]

ok hard drive errors do exist but I wish my car, for example, was as reliable

If I drove a car that was as as unreliable as my hard drives, I'd be dead. Three crashes in the last 4 years, all contents lost.

Re:Anything

[pla (258480)]

Spinning discs on a platter?! A thousand moving parts?! What is this, the Stone Age?!

I know you meant that as a joke, but...

You should take a HDD apart some time. Though manufactured to incredibly small tolerances, they only really have two moving parts - the platters, and the head assembly (which despite having a lot of sub-parts, moves as a single unit).

And aside from them, you don't even have that much else that goes into a HDD - usually two air filters (one for keeping internal air clean, and one that balances external air pressure changes); the body itself (just a big aluminum block with an airtight lid); A magnet assembly for moving the heads; and the electronics on the visible external board. Sometimes you have one more small mechanical bit that doesn't seem to do anything (perhaps it parks the heads for shipping?); And that about covers it.

Re:

[dargaud (518470)]

I understand the need for air to keep the head flying off the surface of the platter. What I don't understand is the need to have a hole to exchange the air with the outside. Can't they just fill it with neutral gas at the optimum pressure and seal the damn thing ? I say that because I've used hard drive at high altitude and they FAIL often. I mean, if they can do it with salad, why can't they do it to HDs ?

Re:Anything

[Nimey (114278)]

They're not sealed because air pressure is a powerful thing. If you take a laptop with a sealed hd on an airplane, the pressure changes in flight could throw various parts out of true. There'd also be metal fatigue just from normal air-pressure changes due to weather.

In other words, the guys who've been designing hard drives for the past few decades aren't stupid.

Re:

[Dogtanian (588974)]

That reminds me of something I'd almost forgotten; the first Amstrad PC clones (*) that my Dad had at work required you to run a utility to "manually" park the heads on the hard drive before you powered down. Or maybe I'm remembering it wrong.

(*) Amstrad is a British company who (amongst other things) sold the first *really* successful PC clones on the UK market.

Re:Anything

[tlhIngan (30335)]

Flash memory is no good because it has a limited number of write cycles (typically about 10,000 - after which it becomes 'random'. If a swap file was on flash memory, it'd soon die..)

Very low-end flash memory has that kind of write cycles. And it's typically limited to NOR flash, which is used only for code memory and limited data store due it its large cell size (largest NOR flash chips are around 256MB). Even so, Intel's StrataFlash had write lifetimes of at least 100,000 erase-write cycles, and most flash chips are underrated by an order of magnitude.

Modern bulk-dsta storage flash is NAND flash, which due to its smaller cell size (partly due to its design, and partly due to operation), means 16GB (byte, not bits) per chip is starting to become practical. NAND flash is faster erasing and writing than NOR flash, but much slower (order of magnitude) slower at reading. Plus it's I/O based - you can't "boot" from NAND flash like you can from NOR. (Write/Erase/Reads are on the order of microseconds for NAND - typically 100-500uS for write/erase, and 10uS for reads. For NOR, writes are typically 300-1000milliseconds, erases 1000ms, but reads on the order of 100ns or less).

Because of the operational characteristics of NAND flash, it typically has a 100,000 write-erase cycle limit at the minimum, with most offering at least 1,000,000 cycles (and typically lasts an order of magnitude more).

Wear-levelling algorithms and bad-block handling increase the time between writes and erases to the point where it almost isn't a consideration anymore - when the drive dies eventually, it'll really be timeto change it. And at least when an SSD dies, it dies on erases and writes, and very rarely on read. So if you get write errors, you still have a great probability of recovering all the data (except the data which was just written).

It's write-erase cycles, because erasing turns "0" bits into "1" bits. Writing turns "1" bits into "0" bits. Within certain restrictions, you can do multiple writes to a block (turning "1" bits into "0" bits, but you can't turn a "0" bit into a "1" bit without erasing), but those don't count towards write-erase cycles. (This behavior is often exploited when marking blocks as dirty and such). And they only fail on writes or erases due to internal timeouts (each cell takes progressively longer and longer to erase and write). Reads can be considered as never failing.

Re:

[comradeeroid (1048432)]

Anything would be better than the current way my hard drive works. Spinning discs on a platter?! A thousand moving parts?! What is this, the Stone Age?!

Well, actually it's worse than the stone age. Back then we had "Monoliths" which (apart from glacial shift and other geological "features" - or "bugs" as anyone outside sales management called them) had no moving (of movable even) parts at all.

When the storage space on a monolith wasn't enough you could expand to a "Circle".
Still, the space on a full c

Who needs nylon?

[Andy_R (114137)]

I just ping foreign servers a lot

there != their

[niceone (992278)]

their location.

I will stop now before I make a simple grammatical error myself.

(yes, I know you're looking, hmm, hmm, must be one here somewhere)

The more things change,

[gillbates (106458)]

The more they stay the same.

For those who don't know, delay line memories [wikipedia.org] have been around for at least 50 years...

Kind of interesting that they are using an old concept with new technologies.

Re:

[AltGrendel (175092)]

I think you mean core memory [wikipedia.org].

No, core memory...

[msauve (701917)]

stores 1 bit per "core." The article is about a form of memory which continually cycles multiple bits stored as magnetic regions through a single physical ring. The OP is correct in that this is similar to cycling photons through an optical ring.

Looking back, this is all very similar to shift register memory, one of the earliest forms of solid state memory.

Re:Sounds like...

[Hal_Porter (817932)]

Actually, it's more like Bubble Memory
http://en.wikipedia.org/wiki/Bubble_memory [wikipedia.org]

Re:

[Intron (870560)]

Bubble memory was like delay-line memory, but retained the data when the power was off. Not clear from the article whether racetrack can be non-volatile, but it needs that to compete with disk.