Hynix 48-GB Flash MCP

Hal_Porter writes to let us know that the third-largest NAND chip maker, Hynix, has announced they have stacked 24 flash chips in a 1.4mm thick multi-chip package. It's not entirely clear from the article whether the resulting 48-GB device is a proof of concept or a product. The article extrapolates to 384 GB of storage in a single package, sometime. Hal_Porter adds: "It's not clear if it's possible to write to them in parallel — if so the device should be pretty damn fast. The usual objection to NAND flash as a hard drive replacement is lifetime. NAND sectors can only be written 100,000 times or so before they wear out, but wear leveling can be done to spread writes evenly over at least each chip. I worked out that the lifetime should be much longer than a typical magnetic hard disk. There's no information on costs yet frankly and it sounds like an expensive proof of concept, but it shows you the sort of device that will take over from small hard disks in the next few years."

Comments

Database servers

[gnuman99]

Random seek is probably one of the biggest bottlenecks in large databases. There are even databases that optimize reads/writes to be more consecutive on the disk. A drive like that would throw that problem out of the window.

Re:Database servers

[CastrTroy]

You'd have to look at how much actual reading or writing to the drive is done by a computer from that era. Currently, hard drive space is really cheap, so we write lots of stuff to the disk, like temp files, log files, swap out programs, and even with some filesystems and operating systems write to the drive every time a file is accessed. A computer from that era wouldn't be writing so much stuff too the hard drive, as hard drives were small and expensive. It would likely only write to the drive when you need a program to save actual human created data, or when you install a new program. Reading would only be done when you start up the computer, a new program, or load a file.

48 GB = 384Gb

[sirket]

The article does not extrapolate to 384 GB of storage- they extrapolate to 384 Gb of storage which is 48 GB of storage. bits != bytes.

Re:Why only 100,000 times

[jandrese]

It's due to the way Flash works. A flash bit is basically a conductor surrounded by an insulator. To store a bit, you apply a large charge to the insulator to increase the charge of the conductor, basically your burning through the insulator to get your charge though. Once it is on there, to read the charge you have to apply another large charge to the insulator and see if the resultant charge is n or n + m. The m factor comes from latent charge on the conductor.

Anyway, the upshot of this is that because you have to constantly burn charge through the insulator to use the part, eventually you basically burn out the insulator and cause it to leak charge. Once it starts leaking, you lose your stored bits and the part is useless.

Flash lifespan in persective

[G4from128k]

Even at only 1,000 writes of reliable lifespan, 48 GB could handle 48 TB of writes or over 4,000 hours of continuous writing of compressed HD video (or about 2 years of 40 hr/week writes of a video stream). Checking my average usage of disk I/O finds that I only average about 2 GB of writes per day which would suggest that this device would last me 24,000 days (or 65 years). And if the life is 10,000 or 100,000, then I'd see 10X or 100X that lifespan.

Your mileage may vary, but I'd bet that 99% of users would never keep their computer (especially a laptop that is the more likely application for flash-based drives) for long enough to see the disk fail from wear.

What about RAID?

[GreatBunzinni]

Recently, this whole flash drive business has been popping up in the news, with announcements of a whole gob of commercial solid-state drives based on flash technology and the like. Nonetheless, there is a big void in the flash drive world that, at least at first glance, could be easily filled with trivial technology and off the shelf products but no one seems to be paying any attention.

I'm talking about RAID + flash cards.

Flash cards are everywhere and, although their cost per GB is rather high, a 1GB card is easily affordable (1GB microSD card for less than 10 euros) and prices are dropping constantly. If someone decided to build a RAID card reader, we could easily get a foot in the door. For about 60 euros it would be possible to get something between a slowish but reliable 6GB flash drive or a speedy and snappy 1GB flash drive.

So why exactly didn't anyone thought of this? We already have IDE CF card readers, some models supporting 2 drives, that can be had for about 6 euros. Why not a RAID flash card reader?

Re:Why only 100,000 times

[networkBoy]

Flash is rated in erase cycles, not write cycles. Erase is the most damaging event to the tunnel oxide layer in the device, which is why they fail.
Flash Cell stackup (same for NOR and NAND, the interconnection of cells determines what type of array it is):

G - gate (metal)
ONO - Oxide/Nitride/Oxide layer
FG - Floating Gate (Poly)
tOx - Tunnel Oxide (very thin)
Si - wafer (NPN/PNP wells) -nB