Living forever – the end of evolution part-3

Read an article yesterday on researchers who had been studying various mammals and trying to determine the number of DNA mutations they accumulate at about the time they die. The researchers found that after about 800 mutations for mole rats, they die, see Nature article Somatic mutation rates scale with lifespan across mammals and Telegraph article reporting on the research, Mystery of why humans die around 80 may finally be solved.

Similarly, at around 3500 mutations humans die, at around 3000 mutations dogs die and at around 1500 mutations mice die. But the real interesting thing is that the DNA mutation rates and mammal lifespan are highly (negatively) correlated. That is higher mutation rates lead to mammals with shorter life spans.

C. Linear regression of somatic substitution burden (corrected for analysable genome size) on individual age for dog, human, mouse and naked mole-rat samples. Samples from the same individual are shown in the same colour. Regression was performed using mean mutation burdens per individual. Shaded areas indicate 95% confidence intervals of the regression line. A shows microscopic images of sample mammalian cels and the DNA strands examined and B shows the distribution of different types of DNA mutations (substitutions or indels [insertion/deletions of DNA]).

The Telegraph article seems to imply that at 800 mutations all mammals die. But the Nature Article clearly indicates that death is at different mutation counts for each different type of mammal.

Such research show one way on how to live forever. We have talked about similar topics in the distant past see …-the end of evolution part 1 & part 2

But in any case it turns out that one of the leading factors that explains the average age of a mammal at death is its DNA mutation rate. Again, mammals with lower DNA mutation rates live longer on average and mammals with higher DNA mutation rates live shorter lives on average.

Moral of the story

if you want to live longer reduce your DNA mutation rates.

c, Zero-intercept LME regression of somatic mutation rate on inverse lifespan (1/lifespan), presented on the scale of untransformed lifespan (axis). For simplicity, the axis shows mean mutation rates per species, although rates per crypt were used in the regression. The darker shaded area indicates 95% CI of the regression line, and the lighter shaded area marks a twofold deviation from the line. Point estimate and 95% CI of the regression slope (k), FVE and range of end-of-lifespan burden are indicated.

All astronauts are subject to significant forms of cosmic radiation which can’t help but accelerate DNA mutations. So one would have to say that the risk of being an astronaut is that you will die younger.

Moon and Martian colonists will also have the same problem. People traveling, living and working there will have an increased risk of dying young. And of course anyone that works around radiation has the same risk.

Note, the mutation counts/mutation rates, that seem to govern life span are averages. Some individuals have lower mutation rates than their species and some (no doubt) have higher rates. These should have shorter and longer lives on average, respectively.

Given this variability in DNA mutation rates, I would propose that space agencies use as one selection criteria, the astronauts/colonists DNA mutation rate. So that humans which have lower than average DNA mutation rates have a higher priority of being selected to become astronauts/extra-earth colonists. One could using this research and assaying astronauts as they come back to earth for their DNA mutation counts, could theoretically determine the impact to their average life span.

In addition, most life extension research is focused on rejuvenating cellular or organism functionality, mainly through the use of young blood, other select nutrients, stem cells that target specific organs, etc. For example, see MIT Scientists Say They’ve Invented a Treatment That Reverses Hearing Loss which involves taking human cells, transform them into stem cells (at a certain maturity) and injecting them into the ear drum.

Living forever

In prior posts on this topic (see parts 1 &2 linked above) we suggested that with DNA computation and DNA storage (see or listen rather, to our GBoS podcast with CTO of Catalog) now becoming viable, one could potentially come up with a DNA program that could

  • Store an individuals DNA using some very reliable and long lived coding fashion (inside a cell or external to the cell) and
  • Craft a DNA program that could periodically be activated (cellular crontab) to access the stored DNA for the individual(in the cell would be easiest) and use this copy to replace/correct any DNA mutation throughout an individuals cells.

And we would need a very reliable and correct copy of that person’s DNA (using SHA256 hashing, CRCs, ECC, Parity and every other way to insure the DNA as captured is stored correctly forever). And the earlier we obtained the DNA copy for an individual human, the better.

Also, we would need a copy of the program (and probably the DNA) to be present in every cell in a human for this to work effectively. .

However, if we could capture a good copy of a person’s DNA early in their life we could, perhaps, sometime later, incorporate DNA code/program into the individual to use this copy and sweep through a person’s body (at that point in time) and correct any mutations that have accumulated to date. Ultimately, one could schedule this activity to occur like an annual checkup.

So yeah, life extension research can continue along the lines they are going and you can have a bunch of point solutions for cellular/organism malfunction OR it can focus on correctly copying and storing DNA forever and creating a DNA program that can correct DNA defects in every individual cell, using the stored DNA.

End of evolution

Yes mammals and that means any human could live forever this way. But it would signify the start of the end of evolution for the human species. That is whenever we captured their DNA copy, from that point on evolution (by mutating DNA) of that individual and any offspring of that individual could no longer take place. And if enough humans do this, throughout their lifespan, it means the end of evolution for humanity as a species

This assumes that evolution (which is natural variation driven by genetic mutation & survival of the fittest) requires DNA variation (essentially mutation) to drive the species forward.

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So my guess, is either we can live forever and stagnate as a species OR live normal lifespans and evolve as a species into something better over time. I believe nature has made it’s choice.

The surprising thing is that we are at a point in humanities existence where we can conceive of doing away with this natural process – evolution, forever.

Photo Credit(s):

Disk rulz, at least for now

Last week WDC announced their next generation technology for hard drives, MAMR or Microwave Assisted Magnetic Recording. This is in contrast to HAMR, Heat (laser) Assisted Magnetic Recording. Both techniques add energy so that data can be written as smaller bits on a track.

Disk density drivers

Current hard drive technology uses PMR or Perpendicular Magnetic Recording with or without SMR (Shingled Magnetic Recording) and TDMR (Two Dimensional Magnetic Recording), both of which we have discussed before in prior posts.

The problem with PMR-SMR-TDMR is that the max achievable disk density is starting to flat line and approaching the “WriteAbility limit” of the head-media combination.

That is even with TDMR, SMR and PMR heads, the highest density that can be achieved is ~1.1Tb/sq.in. The Writeability limit for the current PMR head-media technology is ~1.4Tb/sq.in. As a result most disk density increases over the past years has been accomplished by adding platters-heads to hard drives.

MAMR and HAMR both seem able to get disk drives to >4.0Tb/sq.in. densities by adding energy to the magnetic recording process, which allows the drive to record more data in the same (grain) area.

There are two factors which drive disk drive density (Tb/sq.in.): Bits per inch (BPI) and Tracks per inch (TPI). Both SMR and TDMR were techniques to add more TPI.

I believe MAMR and HAMR increase BPI beyond whats available today by writing data on smaller magnetic grain sizes (pitch in chart) and thus more bits in the same area. At 7nm grain sizes or below PMR becomes unstable, but HAMR and MAMR can record on grain sizes of 4.5nm which would equate to >4.5Tb/sq.in.

HAMR hurdles

It turns out that HAMR as it uses heat to add energy, heats the media drives to much higher temperatures than what’s normal for a disk drive, something like 400C-700C.  Normal operating temperatures for disk drives is  ~50C.  HAMR heat levels will play havoc with drive reliability. The view from WDC is that HAMR has 100X worse reliability than MAMR.

In order to generate that much heat, HAMR needs a laser to expose the area to be written. Of course the laser has to be in the head to be effective. Having to add a laser and optics will increase the cost of the head, increase the steps to manufacture the head, and require new suppliers/sourcing organizations to supply the componentry.

HAMR also requires a different media substrate. Unclear why, but HAMR seems to require a glass substrate, the magnetic media (many layers) is  deposited ontop of the glass substrate. This requires a new media manufacturing line, probably new suppliers and getting glass to disk drive (flatness-bumpiness, rotational integrity, vibrational integrity) specifications will take time.

Probably more than a half dozen more issues with having laser light inside a hard disk drive but suffice it to say that HAMR was going to be a very difficult transition to perform right and continue to provide today’s drive reliability levels.

MAMR merits

MAMR uses microwaves to add energy to the spot being recorded. The microwaves are generated by a Spin Torque Oscilator, (STO), which is a solid state device, compatible with CMOS fabrication techniques. This means that the MAMR head assembly (PMR & STO) can be fabricated on current head lines and within current head mechanisms.

MAMR doesn’t add heat to the recording area, it uses microwaves to add energy. As such, there’s no temperature change in MAMR recording which means the reliability of MAMR disk drives should be about the same as todays disk drives.

MAMR uses todays aluminum substrates. So, current media manufacturing lines and suppliers can be used and media specifications shouldn’t have to change much (?) to support MAMR.

MAMR has just about the same max recording density as HAMR, so there’s no other benefit to going to HAMR, if MAMR works as expected.

WDC’s technology timeline

WDC says they will have sample MAMR drives out next year and production drives out in 2019. They also predict an enterprise 40TB MAMR drive by 2025. They have high confidence in this schedule because MAMR’s compatabilitiy with  current drive media and head manufacturing processes.

WDC discussed their IP position on HAMR and MAMR. They have 400+ issued HAMR patents with another 100+ pending and 75 issued MAMR patents with 46 more pending. Quantity doesn’t necessarily equate to quality, but their current IP position on both MAMR and HAMR looks solid.

WDC believes that by 2020, ~90% of enterprise data will be stored on hard drives. However, this is predicated on achieving a continuing, 10X cost differential between disk drives and (QLC 3D) flash.

What comes after MAMR is subject of much speculation. I’ve written on one alternative which uses liquid Nitrogen temperatures with molecular magnets, I called CAMR (cold assisted magnetic recording) but it’s way to early to tell.

And we have yet to hear from the other big disk drive leader, Seagate. It will be interesting to hear whether they follow WDC’s lead to MAMR, stick with HAMR, or go off in a different direction.

Comments?

 

Photo Credit(s): WDC presentation

Interesting sessions at SNIA DSI Conference 2015

I attended the SNIA Data Storage Innovation (DSI) Conference in Santa Clara, CA last week and ran into a number of old friends and met a few new ones. While attending the conference, there were a few sessions that seemed to bring the conference to life for me.

Microsoft Software Defined Storage Journey

Jose Barreto, Principal Program Manager – Microsoft, spent a little time on what’s currently shipping with Scale-out File Service, Storage Spaces and other storage components of Windows software defined storage solutions. Essentially, what Microsoft is learning from Azure cloud deployments it is slowly but surely being implemented in Windows Server software and other solutions.

Microsoft ‘s vision is that customers can have their own private cloud storage with partner storage systems (SAN & NAS), with Microsoft SDS (Scale-out File Server with Storage Spaces), with hybrid cloud storage (StorSimple with Azure storage) and public cloud storage (Azure storage).

Jose also mentioned other recent innovations like the Cloud Platform System using Microsoft software, Dell compute, Force 10 networking and JBOD (PowerVault MD3060e) storage in a rack.

Some recent Microsoft SDS innovations include:

  • HDD and SSD storage tiering;
  • Shared volume storage;
  • System Center volume and unified storage management;
  • PowerShell integration;
  • Multi-layer redundancy across nodes, disk enclosures, and disk devices; and
  • Independent scale-out of compute or storage.

Probably a few more I’m missing here but these will suffice.

Then, Jose broke some news on what’s coming next in Windows Server storage offerings:

  • Quality of service (QoS) – Windows Server provides QoS capabilities which allows one to limit the IO activity and can be used to specify min and max IOPS or latency at a VM or VHD level. The scale-out storage service will balance the IO activity across the cluster to meet this QoS specification. Apparently the balancing algorithm came from Microsoft Research but Jose didn’t go into great detail on what it did differently other than being “fairer” applying QoS constraints.
  • Rolling upgrades – Windows Server now supports a cluster running different versions of software. Now one can take a cluster node down and update its software and re-activate it into the same cluster. Previously, code upgrades had to take a whole cluster down at a time.
  • Synchronous replication – Windows Server now supports synchronous Storage Replicast the volume level. Previously Storage Replicas were limited to asynch.
  • Higher VM storage resiliency – Windows will now pause a VM rather than terminate it during transient storage interruptions. This allows VMs to sustain operations across transient outages. VMs are in PausedCritical state until the storage comes back and then they are restarted automatically.
  • Shared-nothing Storage Spaces – Windows Storage Spaces can be configured across cluster nodes without shared storage. Previously, Storage Spaces required shared JBOD storage between cluster nodes. This feature removes this configuration constraint and allows JBOD storage to only be accessible fro a single node.

Jose did not name what this  “Vnext” was going to be called and didn’t provide a specific time frame other than it’s coming out shortly.

Archival Disc Technology

Yasumori  Hino from Panasonic and Jun Nakano from Sony presented information on a brand new removable media technology or Cold Storage. Previous to there session there was another one from HDS Federal Corporation on their BluRay jukebox but Yasumori’s and Jun’s session was more noteworthy.The  new Archive Disc is the next iteration in optical storage beyond BlueRay and targeted at long term archive or “cold” storage.

As a prelude to the Archive Disc discussion Yasumori played a CD that was pressed in 1982 (52nd Street, Billy Joel album) on his current generation laptop to show the inherent downward compatibility in optical disc technology.

In 1980 IBM 3480 disk drives were refrigerator sized, multi $10K devices, and held 2.3GB. As far as I know there aren’t any of these still in operation. And IBM/STK tape was reel to reel and took up a whole rack. There may be a few of these devices still operating these days but not many.  I still have a CD collection (but then I am a GreyBeard 🙂 that I still listen to occasionally.

IMG_4399The new Archive Disc includes:

  • More resilient media to high humidity, high temperature, salt water, and EMP and other magnetic disturbances. As proof, a BlueRay disk was submerged in sea water for 5 weeks and was still able to be read. Data on BlueRay and the new Archive disk is recorded without using electro magnetics and is recorded in a very stable oxide recording material layer. They project that the new Archive disc has a media life of 50 years at 50C and 1000 years at 25C under high humidity conditions.
  • Dual sided, triple layered which uses land and groove recording to provide 300GB of data storage. BlueRay also uses a land and groove disk format but only records on the land portion of the disc. Track pitch for BlueRay is 320nm whereas for the Archive disc it’s only 225nm.
  • Data transfer speeds of 90MB/sec with two optical heads, one per side. Each head can read/write data at 45MB/sec. They project double or quadrouple this data transfer rate by using more pairs of optical heads .

They also presented a roadmap for a 2nd gen 500GB and 3rd gen 1TB Archive disc using higher linear density changes and better signal processing technology.

Cold storage is starting to get some more interest these days what with all the power consumption going into today’s data centers and the never ending data tsunami. Archive and BluRay optical storage consume no power at rest and only consume power when mounting/dismounting and reading/writing/spinning. Also with optical discs imperviousness to high temp and humidity, optical storage could be stored outside of air conditioned data centers.

The Storage Revolution

The final presentation of interest to me was by Andrea Nelson from Intel. Intel has lately been focusing on helping partners and vendors provide more effective storage offerings. These aren’t storage solutions but rather storage hardware, components and software developed in collaboration with storage vendors and partners that make it easier for them to offer storage solutions using Intel hardware. One example of this collaboration is IBM hardware assist Real Time Compression available on new V7000 and FlashSystem V9000 storage hardware.

As the world turns to software defined storage, Intel wants those solutions to make use of their hardware. (Although, at the show I heard from one another new SDS vendor that was planning to use X86 as well as ARM servers).

Intel has:

  • QuickAssist Acceleration technology – such as hardware assist data compression,
  • Storage Acceleration software libraries – open source erasure coding and other low-level compute intensive functions, and
  • Cache Acceleration software – uses Intel SSDs as a data cache for storage applications.

There wasn’t of a technical description of these capabilities as in other DSI sessions but with the industry moving more and more to SDS, Intel’s got a vested interest in seeing it be implemented on their hardware.

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That’s about it. I sat in on quite a number of other sessions but nothing else stuck out as significant or interesting to me as these threes sessions.

Comments?

Optical discs for Facebook cold storage

I heard last week that Facebook is implementing Blu Ray libraries for cold storage. Each BluRay disk holds ~100GB and they figure they can store 10,000 discs or ~1PB in a rack.

They bundle 12 discs in a cartridge and 36 cartridges in a magazine, placing 24 magazines in a cabinet, with BluRay drives and a robotic arm. The robot arm sits in the middle of the cabinet with the magazines/cartridges located on each side.

It’s unclear what Amazon Glacier uses for its storage but a retrieval time of 3-5 hours indicates removable media of some type.  I haven’t seen anything on Windows Azure offering a similar service but Google has released Durable Reduced Availability (DRA) storage which could potentially be hosted on removable media as well.  I was unable to find any access times specifications for Google DRA.

Why the interest in cold storage?

The article mentioned that Facebook is testing the new technology first on its compliance data. After that Facebook will start using it for cold photo storage. Facebook also said that it will be using different storage technologies for it’s cold storage repository mentioning “bad flash” as another alternative.

BluRay supports both a re-writeable as well as WORM (write once, read many times) technology. As such, WORM discs cannot be modified, only destroyed.  WORM technology would be very useful for anyone’s compliance data. The rewritable Blu Ray discs might be more effective for cold photo storage, however the fact that people on Facebook rarely delete photos, says WORM would work well here too.

100GB is a pretty small storage bucket these days but for compliance documents, such as email, invoices, contracts, etc. it’s plenty large.

Can Blu Ray optical provide data center cold storage?

Facebook didn’t discuss the specs on the robot arm that they were planning to use but with 10K cartridges it has a lot of work to do. Tape library robots move a single cartridge in about 11 seconds or so. If the optical robot could do as well (no information to the contrary) one robot arm could support ~4K disc moves per day. But that would be enterprise class robotics and 100% duty cycle, more likely 1/2 to 1/4 of this would be considered good for an off the shelf system like this. So maybe a 1000 to 2000 disc picks per day.

If we use 22 seconds per disc swap (two disc moves), a single robot/rack could support a maximum of 100 to 200TB of data writes per day (assuming robot speed was the only bottleneck).  In the video (see about 30 minutes in) the robot didn’t look all that fast as compared to a tape library robot, but maybe I am biased.

Near as I can tell a 12x BluRay drive can write at ~35MB/sec (SATA drive, writing single layer, 25GB disc, we assume this can be sustained for a 4-layer or dual-sided 2-layer 100GB disc). So to be able to write a full 100GB disk would take ~48 minutes and if you add to that the 22 seconds of disc swap time, one SATA drive running 100% flat out could maybe write 30 discs per day or ~3TB/day.

In the video, the BluRay drives appear to be located in an area above the disc magazines along each side. There appears to be two drives per column with 6 columns per side, so a maximum of 24 drives. With 24 drives, one rack could write about 72TB/day or 720 discs per day which would fit into our 22 seconds per swap.  At 72TB/day it’s going to take ~14 days to fill up a cabinet. I could be off on the drive count, they didn’t show the whole cabinet in the video, so it’s possible they have 12 columns per side, 48 drives per cabinet and 144TB/day.

All this assumes 100% duty cycle on the drives which is unreasonable for an enterprise class tape drive let alone a consumer class BluRay drive. This is also write speed, I assume that read speed is the same or better. Also, I didn’t see any servers in the cabinet and I assume that something has to be reading, writing and controlling the optical library. So these other servers need to be somewhere close by, but they could easily be located in a separate rack somewhere near to the library.

So it all makes some amount of sense from a system throughput perspective. Given what we know about the drive speed, cartridge capacity and robot capabilities, it’s certainly possible that the system could sustain the disc swaps and data transfer necessary to provide data center cold storage archive.

And the software

But there’s plenty of software that has to surround an optical library to make it useful. Somehow we would want to be able to identify a file as a candidate for cold storage then have it moved to some cold storage disc(s), cataloged, and then deleted from the non-cold storage repository.  Of course, we probably want 2 or more copies to be written, maybe these redundant copies should be written to different facilities or at least different cabinets.  The catalog to the cold storage repository is all important and needs to be available 24X7 so this needs to be redundant/protected, updated with extreme care, and from my perspective on some sort of high-speed storage to handle archives of 3EB.

What about OpenStack? Although there have been some rumblings by Oracle and others to provide tape support in OpenStack, nothing seems to be out yet. However, it’s not much of a stretch to see removable media support in OpenStack, if some large company were to put some effort into it.

Other cold storage alternatives

In the video, Facebook says they currently have 30PB of cold storage at one facility and are already in the process of building another. They said that they should have 150PB of cold storage online shortly and that each cold storage facility is capable of holding 3EB or 3,000PB of cold storage.

A couple of years back at Hitachi in Japan, we were shown a Blu Ray optical disc library using 50GB discs. This was just a prototype but they were getting pretty serious about it then. We also saw an update of this at an analyst meeting at HDS, a year or so later. So there’s at least one storage company working on this technology.

Facebook, seems to have decided they were better off developing their own approach. It’s probably more dense/space efficient and maybe even more power efficient but to tell that would take some spec comparisons which aren’t available from Facebook or HDS just yet.

Why not magnetic tape?

I see these large storage repository sizes and wonder if Facebook might not be better off using magnetic tape. It has a much larger capacity and I believe magnetic tape (LTO or enterprise) would supply better volumetric (bytes/in**3) density than the Blu Ray cabinet they showed in the video.

Facebook said that BluRay discs had a 50 year lifetime.  I believe enterprise and LTO tape vendors say their cartridges have a 30 year lifetime. And that might be one consideration driving them to optical.

The reality is that new LTO technology is coming out every 2-3 years or so, and new drives read only 2 generations back and write only the current technology. With that quick a turnover, a data center would probably have to migrate data from old to new tape technology every decade or so before old tape drives go out of warranty.

I have not seen any Blu Ray technology roadmaps so it’s hard to make a comparison, but to date, PC based Blu Ray drives typically can read and write CDs, DVDs, and current Blu Ray disks (which is probably 4 to 5 generations back). So they have a better reputation for backward compatibility over time.

Tape technology roadmaps are so quick because tape competes with disk, which doubles capacity every 18 months or so. I am sure tape drive and media vendors would be happy not to upgrade their technology so fast but then disk storage would take over more and more tape storage applications.

If Blu Ray were to become a data center storage standard, as Facebook seems to want, I believe that Blu Ray technology would fall under similar competitive pressures from both disk and tape to upgrade optical technology at a faster rate. When that happens, it would be interesting to see how quickly optical drives stop supporting the backward compatibility that they currently support.

Comments?

Photo Credit: [73/366] Grooves by Dwayne Bent [Ed. note, picture of DVD, not Blu Ray disc]

 

 

Heating NAND brings it back to life

Read an article today in ARS Technica titled NAND flash gets baked, lives longer that researchers at Macronix have come up with a technique that rejuvenates NAND bit cells by heating them.  The process releases the bit cells captive electrons and returns it back to a fresh NAND cell.

As discussed previously in this blog (e.g., see The End of NAND is near, maybe… and What eMLC and eSLC do for SSD longevity) as NAND technology shrinks to smaller transistor diameters, their longevity and durability decreases proportionally. Which means that with denser NAND chips coming out over the coming years, they will become increasingly short lived.

With this new approach and an awful lot of engineering to zap a NAND bit cell with intense heat (800C) can take dead NAND cells and bring them back to life. Apparently this rejuvenation process has been known for some time and had been in use for phase change memory but had not been applied to NAND cells in memory.  They were heating batches of NAND cells for hours at 200C but this wouldn’t be very practical in production.

The new NAND memory cells are designed with a resistive heating element on top of them, which when enabled can heat the NAND bit cells beneath them. According to some news reports I’ve read this enables the NAND cell to go from 10K P/E cycles to 100K P/E cycles.  And the heat only needs to be applied in occasional pulses to keep cells operating within parameters.   As such, it can be used sparingly and not cost too much energy in the process.

Another side effect of heating is that erase cycles operate faster than at normal temperatures, which now adds the possibility of heat assisted NAND cells.   Erasure being one of the key bottlenecks to NAND write performance anything that can speed this up would help.

Hot NAND may have some life in them after all.

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Comments?

Image: Blow Torch by xlibber

The end of NAND is near, maybe…

In honor of today’s Flash Summit conference, I give my semi-annual amateur view of competing NAND technologies.

I was talking with a major storage vendor today and they said they were sampling sub-20nm NAND chips with P/E cycles of 300 with a data retention period under a week at room temperatures. With those specifications these chips almost can’t get out of the factory with any life left in them.

On the other hand the only sub-20nm (19nm) NAND information I could find online were inside the new Toshiba THNSNF SSDs with toggle MLC NAND that guaranteed data retention of 3 months at 40°C.   I could not find any published P/E cycle specifications for the NAND in their drive but presumably this is at most equivalent to their prior generation 24 nm NAND or at worse somewhere below that generations P/E cycles. (Of course, I couldn’t find P/E cycle specifications for that drive either but similar technology in other drives seems to offer native 3000 P/E cycles.)

Intel-Micron, SanDisk and others have all recently announced 20nm MLC NAND chips with a P/E cycles around 3K to 5K.

Nevertheless, as NAND chips go beyond their rated P/E cycle quantities, NAND bit errors increase. With a more powerful ECC algorithm in SSDs and NAND controllers, one can still correct the data coming off the NAND chips.  However at some point beyond 24 bit ECC this probably becomes unsustainable. (See interesting post by NexGen on ECC capabilities as NAND die size shrinks).

Not sure how to bridge the gap between 3-5K P/E cycles and the 300 P/E cycles being seen by storage vendors above but this may be a function of prototype vs. production technology and possibly it had other characteristics they were interested in.

But given the declining endurance of NAND below 20nm, some industry players are investigating other solid state storage technologies to replace NAND, e.g.,  MRAM, FeRAM, PCM and ReRAM all of which are current contenders, at least from a research perspective.

MRAM is currently available in small capacities from Everspin and elsewhere but hasn’t really come up with similar densities on the order of today’s NAND technologies.

ReRAM is starting to emerge in low power applications as a substitute for SRAM/DRAM, but it’s still early yet.

I haven’t heard much about FeRAM other than last year researchers at Purdue having invented a new non-destructive read FeRAM they call FeTRAM.   Standard FeRAMs are already in commercial use, albeit in limited applications from Ramtron and others but density is still a hurdle and write performance is a problem.

Recently the PCM approach has heated up as PCM technology is now commercially available being released by Micro.  Yes the technology has a long way to go to catch up with NAND densities (available at 45nm technology) but it’s yet another start down a technology pathway to build volume and research ways to reduce cost, increase density and generally improve the technology.  In the mean time I hear it’s an order of magnitude faster than NAND.

Racetrack memory, a form of MRAM using wires to store multiple bits, isn’t standing still either.  Last December, IBM announced they have demonstrated  Racetrack memory chips in their labs.  With this milestone IBM has shown how a complete Racetrack memory chip could be fabricated on a CMOS technology lines.

However, in the same press release from IBM on recent research results, they announced a new technique to construct CMOS compatible graphene devices on a chip.  As we have previously reported, another approach to replacing standard NAND technology  uses graphene transistors to replace the storage layer of NAND flash.  Graphene NAND holds the promise of increasing density with much better endurance, retention and reliability than today’s NAND.

So as of today, NAND is still the king of solid state storage technologies but there are a number of princelings and other emerging pretenders, all vying for its throne of tomorrow.

Comments?

Image: 20 nanometer NAND Flash chip by IntelFreePress

Graphene Flash Memory

Model of graphene structure by CORE-Materials (cc) (from Flickr)
Model of graphene structure by CORE-Materials (cc) (from Flickr)

I have been thinking about writing a post on “Is Flash Dead?” for a while now.  Well at least since talking with IBM research a couple of weeks ago on their new memory technologies that they have been working on.

But then this new Technology Review article came out  discussing recent research on Graphene Flash Memory.

Problems with NAND Flash

As we have discussed before, NAND flash memory has some serious limitations as it’s shrunk below 11nm or so. For instance, write endurance plummets, memory retention times are reduced and cell-to-cell interactions increase significantly.

These issues are not that much of a problem with today’s flash at 20nm or so. But to continue to follow Moore’s law and drop the price of NAND flash on a $/Gb basis, it will need to shrink below 16nm.  At that point or soon thereafter, current NAND flash technology will no longer be viable.

Other non-NAND based non-volatile memories

That’s why IBM and others are working on different types of non-volatile storage such as PCM (phase change memory), MRAM (magnetic RAM) , FeRAM (Ferroelectric RAM) and others.  All these have the potential to improve general reliability characteristics beyond where NAND Flash is today and where it will be tomorrow as chip geometries shrink even more.

IBM seems to be betting on MRAM or racetrack memory technology because it has near DRAM performance, extremely low power and can store far more data in the same amount of space. It sort of reminds me of delay line memory where bits were stored on a wire line and read out as they passed across a read/write circuit. Only in the case of racetrack memory, the delay line is etched in a silicon circuit indentation with the read/write head implemented at the bottom of the cleft.

Graphene as the solution

Then along comes Graphene based Flash Memory.  Graphene can apparently be used as a substitute for the storage layer in a flash memory cell.  According to the report, the graphene stores data using less power and with better stability over time.  Both crucial problems with NAND flash memory as it’s shrunk below today’s geometries.  The research is being done at UCLA and is supported by Samsung, a significant manufacturer of NAND flash memory today.

Current demonstration chips are much larger than would be useful.  However, given graphene’s material characteristics, the researchers believe there should be no problem scaling it down below where NAND Flash would start exhibiting problems.  The next iteration of research will be to see if their scaling assumptions can hold when device geometry is shrunk.

The other problem is getting graphene, a new material, into current chip production.  Current materials used in chip manufacturing lines are very tightly controlled and  building hybrid graphene devices to the same level of manufacturing tolerances and control will take some effort.

So don’t look for Graphene Flash Memory to show up anytime soon. But given that 16nm chip geometries are only a couple of years out and 11nm, a couple of years beyond that, it wouldn’t surprise me to see Graphene based Flash Memory introduced in about 4 years or so.  Then again, I am no materials expert, so don’t hold me to this timeline.

 

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M-Disc provides a 1000 year archivable DVD

M-Disc (c) 2011 Millenniata (from their website)
M-Disc (c) 2011 Millenniata (from their website)

I heard about this last week but saw another notice today.  Millenniata has made what they believe to be a DVD which has a 1000 year archive life they call the M-Disc .

I have written before about the lack of long term archives for digital data mostly focused on disappearing formants but this device if it works, has the potential to solve the other problem (discussed here) mainly that no storage media around today can last that long.

The new single layer DVD (4.7GB max) has a chemically stable, inorganic recording layer which is a heat resistant matrix of materials which can retain data while surviving temperatures of up to 500°C (932°F).

Unlike normal DVDs which record data using organic dyes within a DVD, M-Disc data is recorded on this stone-like layer embedded inside  the DVD.  By doing so, M-Disc have created the modern day equivalent of etching information in stone.

According to the vendor, M-Disc archive-ability was independently validated by the US DOD at their Church Lake facilities. While the DOD didn’t say the M-Disc DVD has a 1000 year life they did say that under their testing the M-Disc was the only DVD device which did not lose data. The DOD tested DVDs from Mitsubishi, Verbatum, Delkin, MAM-A and Taiyo Yuden (JVC) in addition to the M-Disc.

The other problems with long term archives involve data formats and program availability that could read such formats from long ago. Although Millenniata have no solution for this, something like a format repository with XML descriptions might provide the way forward to a solution.

Given the nature of their DVD recording surface, special purpose DVD writers, with lasers that are 5X the intensity of normal DVDs, need to be used. But once recorded any DVD reader is able to read the data off the disk.

Pricing for the media was suggested to be about equivalent per disk for archive quality DVDs.  Pricing for the special DVD writers was not disclosed.

They did indicate they were working on a similar product for BluRay disks which would take the single layer capacity up to 26GBs.

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