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."

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.

swap space / tmpfs / cacheing

[lobiusmoop]

Given the low price of RAM these days (1 or 2 gigs being standard) minimising the need for swapping, and availability of tmpfs in the Linux kernel, I'm surprised there are not more flashdrive based linux boxes available these days.

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.

Re:Why only 100,000 times

[Bacon Bits]

It's wholly one of mechanical endurance of the components, AFAIK. The gate is wedged, for lack of a better term. Everything physical wears out. It was much worse in the early 1990s, but whole orders of magnitude in improved performance have been made since then.

I've never seen a study conclude that the write limitation on NAND flash-based devices is a significant impact. Some of the studies have cited worst case scenarios of 50 years of continuous operation. It is far more likely that the device will physically fail due to other means rather than fail due to NAND erasing wear. In any case, I've never seen anyone claim that a solid state disk is going to fail before a mechanical magnetic disk simply due to NAND erasing wear. Indeed, the articles that actually go into it make pretty strong claims that the endurance of flash media is far above that of current mechanical-electromagnetic designs. Three or four times the lifespan.

Re:swap space / tmpfs / cacheing

[Com2Kid]

2GB SD cards are still a better band for your buck, typically. In the very least, compatibility is better. :)

You can get them pretty easily for $20 a pop.

Amazingly enough Amazon has 2GB SD cards cheaper than Newegg. $15 a pop (no free shipping though!)

That is $30 for 4GB, or $60 for 8GB.

Not quite enough to get Vista up and running, but it should do fine for a stand alone Linux box. :-D

I wonder what the throughput would be if a proper hardware controller was put in place and you had 50 of those things in parallel.

Re:swap space / tmpfs / cacheing

[Anonymous Coward]

I'm surprised there are not more flashdrive based linux boxes available these days.

There will be several million shortly...

# Mass storage: 1024 MiB SLC NAND flash, high-speed flash controller;
# Drives: No rotating media.

From the OLPC Spec [laptop.org]

Re:Database servers

[Surt]

http://download.micron.com/pdf/datasheets/flash/na nd/4gb_nand_m40a.pdf [micron.com]
promises data retention of 10 years. I would guess that it will function longer than that, but only if you refresh the data.

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:swap space / tmpfs / cacheing

[Spokehedz]

I can't find it now, but I remember a device that would take a bunch of SD cards (like, 4 slots) and would combine them into a big disk that had (I believe) SATA on it. So, you would take a bunch of these cheap 2GB SD cards, and it would make one big disk out of them all.

http://www.geekstuff4u.com/product_info.php?manufa cturers_id=&products_id=492 [geekstuff4u.com]

Not it, but close. Also way too expensive.

Re:Flash lifespan in persective

[msgtomatt]

Your calculation of 24,000 days is when the drive reaches total failure. Your logic does apply to camcorder applications in which data is always written sequentially. But, in PC applications you do not write the information as a bit stream, you write things fairly randomly. When you change the contents of a file without changing the file size, you update the same physical memory locations. So after you update your file a 1,000 times, it becomes corrupted and you loose your data. Once a single byte becomes corrupted the entire sector can longer be used. So in the worse case scenario, this fancy drive would not even last you a day, before you started to loose information.

To prevent data loss, these drives will require a good CRC algorithm or a RAID configuration that can repair damaged files when they are moved to new sectors. Also, it might be possible to convert the random access to sequential access, by moving the file the end of a circular stream buffer every time it is written too. But this would lead to fragmentation problems, that might be impossible to solve.