Will flash ever be cheap as disk?

Will flash ever be cheap as disk?

Summary: No. Transistors will always cost more than tiny magnetic dots, despite Moore's Law. Here's why.

TOPICS: Storage, Hardware

The math seems simple enough: semiconductor prices keep plunging at a steady 40% annually. In the aughts disk drives exceeded that for a several years, but now are moving much slower.  Flash will catch up with disk and then goodbye, rotating rust!

But that will never happen - and yes, I know that forever is a long time. But why?

Several reasons.

Steep climb
The cheapest hard drives are now down to $0.03/GB. The cheapest flash chips now average about $0.80/GB on the spot market - or about 27x. Even if flash continues its 40% path, with disk at only 25%, it will take many years to close the gap.

But the preceding example is an apples-to-oranges comparison. A flash chip is only equivalent to the disks and heads of a disk - not the entire disk. Much of the remaining overhead will remain the same: power; R/W chips; circuit boards; and packaging. So even if flash chips magically dropped to $0.03/GB they'd still be more expensive than disks, because of the device overhead.

Slower, worse & cheaper
Unlike other semiconductors that get faster, use less power and are more reliable as they shrink, NAND flash cells get slower and less reliable as they shrink while their power requirements remain the same. Write endurance has dropped from 10,000 to less than 1,000 in the last few years. Data retention time is also less. Three and 4 level cells will drop that even more.

Not a problem for consumer devices where the average cell sees a few dozen writes at most over its life. A big problem for SSDs, requiring all sorts of additional logic and over-provisioning at additional cost.

ReRAM to the rescue
In the next 5 years SSDs will have to move to a new technology. ReRAM (resistance RAM) is the likeliest candidate. Great stuff, but it will take years before it is as cheap as flash.

Disks aren't standing still
Will disks ever get back on the 40% declining cost curve? Not likely. With the slow collapse of PC sales, the investments needed for patterned media and advanced recording technologies are less inviting. But they'll get there.

The Storage Bits take
Despite the price differential, many consumers, like me, will choose a flash drive - or a flash-based mobile device - over a disk drive. But all those cloud-based services? Disks - lots and lots of disks - with perhaps some flash and/or DRAM based caching appliances on the front end.

Yes, flash is eating away at the disk market, but more in the form of flash-based smartphones and tablets than SSDs. PCs have been the largest single disk market for decades. As PC sales continue to decline, disk sales go with them.

The real threat to disks is not cheap flash - which will never be cheap enough to compete directly - but the next gen in solid-state storage: ReRAM. ReRAM will scale better, write faster and endure longer than current and future NAND generations. Storage people will pay extra for all those benefits.

But we'll see how that develops.

Comments welcome, as always.  Hybrid drives will boost disk performance at lower cost, making SSDs less attractive for consumers, don't you think?

Topics: Storage, Hardware

Kick off your day with ZDNet's daily email newsletter. It's the freshest tech news and opinion, served hot. Get it.


Log in or register to join the discussion
  • Say WHAT?

    I think Robin needs to read more current specs. In the 16GB size, retail prices are lower than the $.80/GB now, and the write life is orders of magnitude greater than stated.
    • Sorry to break this to you, but . . .

      I look at spot market prices posted on DRAMexchange. Yes, there are cheaper chips - vendor binning culls the marginal units for open market sale - but building SSDs from them is a great way to hose your brand and your sales. Thumb drive users are more forgiving.

      And no, specs are not "orders of magnitude greater." Controller designers, like LSI, Fusion-io, Apple and others do all sorts of magic to much extend the life of NAND cells, but that doesn't change the specs.

      R Harris
      • you rather glossed over the power consumption factor

        The longer an SSD is in service, the more it closes the "total cost of ownership" gap until it passes right by the HDD and leaves it behind. Your "comparison" needs to be more than a snapshot.
    • But

      they're also as slow as all getout. They're great for portable/handheld/embedded, but you wouldn't want those as SSDs in your laptop or desktop because it would be more expensive than magnetic AND it would be about the same speed if not a little slower.
      Jacob VanWagoner
      • Umm

        I think your info is a little outdated. A Western Digital Raptor at 10,000 rpm is about 90MB/sec read. The little Macbook Air SSD can read at 671MB/sec. I put an SSD in my laptop and desktop and holy shiz it's like night and day faster.
  • You are totally over looking ....

    The long term storage sectors. For years now (a decade I guess), I've been replacing my customer's old tape archive systems with on-line, long-term storage. When you can get a 3TB drive for under $150 and performance is NOT the primary issue, why would you want a more expensive, less performing, and much smaller storage device? Ok, sure, the "consumer" market is different...but by how much? By now most people have (hopefully) suffered their "Ah Ha" data disaster and understand the importance of backing up. The "cloud" offers some advantages (so say its proponents) but nothing beats a 2TB external USB storage drive .... for under $100.00

    Yes, perhaps the "PC" hard drive will be hurt to some degree by the "post-pc" era (which I don't buy into) but data storage is INCREASING, not decreasing, regardless of the device used to create such data. Therefore, storage will continue to be in big demand and nothing on the horizon comes close to the cost/benefit ratio of the traditional hard drive.
    • Google & Amazon drive a hard bargain

      You are correct that demand is increasing - thanks, NSA! - and as tape drive volumes drop and tape media prices keep rising for the required advanced formulations, disks are more cost effective for more apps. But Amazon's buyers have very sharp pencils and buy in huge volumes, limiting the margin HDD manufacturers can get. Hybrid HDDs will help, but WD and Seagate are now focused on vacuuming up the under $25k storage system market - consumer, prosumer, SOJHO and SMB - to get better margins. And its working.

      R Harris
  • It doesn't matter whether it's /as/ cheap...

    ...but whether it's cheap /enough/.

    When I bought a new computer last year, the boot drive was a 256GB SSD, for all the obvious reasons. Everything else (including most software) went to a 2TB RAID 5 array.

    The SSD wasn't "cheap", but its advantages outweighed the cost.
  • Backing up

    Ccs9623 says "nothing beats a 2TB external USB storage drive

    Not quite right.

    Nothing beats a 2TB external USB storage drive PLUS online offsite/cloud storage...

    A burglar or fire will 'take' the external HDD as quickly as the main computer.
  • It's not just Moore's law

    it's the price of electronics grade silicon versus hard-drive grade iron, normalized by the volume it takes to store one bit.
    Jacob VanWagoner
  • I built a Computer Power specs and............

    My boot drive was a 480Gb Corsair Force GS SSD Deivce and the other drives are WD 1Tb drives in RAID.

    I very happy
  • Will flash ever be cheap as disk? NOPE!

    Until something better comes along, demand for flash will continue to grow - and portability will be the order of the day. SSD technology is finally down to around $1 per GB. Flash can be as low as $0.50 per GB.

    HDD will always be cheaper (now under $0.10 per GB for 3.5" TB drives) - these are approaching commodity price-points. Before SSD's reach the $0.10 per GB level, demand for consumer-grade HDDs will be discontinued - because the manufacturing costs will exceed the demand.
    M Wagner
  • Read Mostly Storage

    Files that are seldom changed, but need to be read frequently and quickly, are the best app for flash/SSD technology, because of the limited write lifetime; so the boot drive is an excellent application for such devices. Archive files as well, provided there are multiple redundant backups; and each archive event should only append files in empty space, not reorganize or defrag or delete old ones. In other words, the backup design would behave almost as if it were writing on an un-finalized CD-R.