Slashdot Mirror

← Back to Stories (view on slashdot.org)

NAND Flash Density Surpasses HDDs', But Price Is Still a Sticking Point (computerworld.com)

Posted by timothy on from the daddy-what-were-spinning-media-and-what-was-their-areal-density? dept.

Lucas123 writes: With the introduction of 3D or stacked NAND flash memory, non-volatile memory has for the first time surpassed that of hard disk drives in density. This year, Micron revealed it had demonstrated areal densities in its laboratories of up to 2.77 terabits per square inch (Tbpsi) for its 3D NAND. That compares with the densest HDDs of about 1.3Tbpsi. While NAND flash may have surpassed hard drives in density, it doesn't mean the medium has reached price parity with HDDs — nor will it anytime soon. One roadblock to price parity is the cost of revamping existing or building new 3D NAND fabrication plant, which far exceeds that of hard drive manufacturing facilities, according to market research firm Coughlin Associates. HDD makers are also preparing to launch even denser products using technologies such as heat assisted magnetic recording.

7 of 185 comments (clear)

  1. Density is nice, but what about longevity? by kheldan · · Score: 5, Interesting

    Have SSD's reached a point where they have a lifespan comparable to HDD's in the most extreme applications, though? For instance: Just had to replace the HDD in my DVR. It's dual tuner so it's buffering 30 minutes for each channel, perpetually. The HDD lasted for years; would a current-technology SSD last as long before it ran out of write cycles in the flash memory?

    --
    Are YOU using the TOOL, or is the TOOL using YOU? Think about it!
    1. Re:Density is nice, but what about longevity? by AnotherBlackHat · · Score: 5, Informative

      OTA channels = 19.38 Mbps (max)
      2 channels = 38.76 Mbps = 4.845 MB/sec
      1 Terabyte SSD = 1,000,000 MB
      1,000,000 / 4.845 = 206,398 seconds, or 2.3 days
      Nand flash write cycle life : 10,000

      Total life 10,000 * 2.3 days = 23,000 days or 65 years

      If you don't like the assumptions, feel free to make your own, but I think it's clear that write cycle life isn't going to be the limiting factor.

    2. Re:Density is nice, but what about longevity? by LordKronos · · Score: 4, Informative

      The largest recording I've ever seen off of cable TV is about 8GB/hr. I know OTA broadcasts can be slightly bigger, so lets say 10GB/hr. To record that 24/7 requires about 87 TB/year.

      There was a long term test of SSDs done here:
      http://techreport.com/review/2...

      Many of the drives ended up getting close to 1 PB of writes, and the best even got over 2PB. Thats enough for you to run 2 tuners 24/7 for a decade. And note, their tests were with 250GB drives. As you increase SSD capacity, longevity increases almost linearly. If you were building a DVR, you'd probably want something like a 1TB drive.

      As far as the original question of whether the SSD can outlive HDD in the most extreme application....probably at the most extreme, no. But for the vast majority of cases, including a DVR, most likely yes.

    3. Re:Density is nice, but what about longevity? by nneonneo · · Score: 5, Informative

      Let's work it out. A few years ago, TechReport ran an SSD endurance experiment to figure out how much punishment current-gen SSDs could take before failing. Their test setup essentially involved writing random data at maximum speed for 18 months straight. The results indicated that the worst SSD in their bunch, a Intel's 335 Series, wrote about 700 TB before dying, and the best SSD, a Samsung 840 Pro SSD, went on to 2.4 PB.

      Various estimates say you can put between 60-75 hours of HD content on a 500GB drive, so, assuming the largest possible size, that works out to about 8.3 GB/hour. Since you're writing two streams, that's 16.6 GB/hour, or 145 TB per year. For the worst drive in the bunch, that's about 4.8 years of service (right at the upper end of your HDD's service life); for the best drive, it's over 16 years.

      Keep in mind that these tests were all run on 250GB drives. Smaller drives have less flash to work with, and have to write over the same flash cells more often. Therefore, if you bought a 1TB drive, you can expect the lifetime to be easily 4x better (more if you're using a more recent drive, such as the Samsung 850 Pro) - 64 years of DVR recording should be more than sufficient.

  2. Flash won already by jones_supa · · Score: 4, Insightful

    If you look at a list of new computers, you will notice that a surprisingly large amount of PCs are already shipping with 128 GB or 256 GB SSD. That's gonna hold everything that most people need. People with bit more specialized needs (hardcore gaming, media production, virtual machines, etc.) can probably soon acquire 1 TB SSD for a price like $200. Only massive data centers will remain as users of HDDs. Flash memory companies are putting huge investments in developing the technology further, while HAMR is still a prototype in skunkworks that is struggling to be usable for mass production.

    1. Re:Flash won already by Nemyst · · Score: 4, Interesting

      The thing that might dislodge NAND is Intel/Micron's new 3D Xpoint, which is supposedly much faster, allows for bit-level writes and is just as durable if not more so than NAND. It's also supposed to be available shortly.

  3. Re:Price Is Still Just One of Two Sticking Points by ShooterNeo · · Score: 4, Informative

    That isn't how wear leveling algorithm work. Yes, once you hit 99%, every write does involve a rewrite somewhere, but those writes are not concentrated in the 1% free area. Instead, the drive controller is reading sections of already written disk and moving them around.