SSD reliability lower than disks?

SSD reliability lower than disks?

Summary: Recent reports suggest that SSD's are no more reliable than 1 TB hard drives. Given that few SSDs are 1 TB, the reliability per bit is much lower for SSDs. Why?


Recent evidence suggests that SSD's are no more reliable than 1 TB hard drives. Given that few SSDs are 1 TB, the reliability per bit is much lower for SSDs. Why?

Background A French site specializing in Mac systems got data from a French retailer on disk and SSD returns. They saw about the same failure rate for SSD's as they did for 1 TB hard drives. More recent 2 TB hard drives were less reliable. Not a surprise since it takes time for the manufacturing processes to mature.

These findings are surprising if you consider flash chips to be like the thousands of other integrated circuits that you use every day. IC reliability is impressive and it is not uncommon for a chip to work flawlessly for a decade or more.

But flash chips aren't like other chips: they require ?20 volts to write data. In the chip world, where insulating layers may only be a few molecules thick, 20 V is a lot of electrical pressure.

Wait a minute, you might think, there isn't a single flash chip that specifies a 20 V or even in 15 V power requirement. And you would be correct.

Flash chips have power specs like other chips. What's different is that flash chips have on-board electrical pumps - in the form of dedicated capacitors and an oscillator - that take supply voltage and convert it to the higher voltage needed to write a flash cell.

Here is a recent annotated chip photograph, courtesy of Toshiba Corporation (the folks who invented flash) that shows the chip area devoted to the pump function.

The Storage Bits take Storage is the most difficult problem in computers. Moving bits through a pipe is easy. Storing bits for years is hard.

It is no surprise that devices composed of multiple high-voltage flash chips may have infant mortality rates similar to disk drives. After all, we've been building disk drives for over 50 years and the advances in density, capacity and reliability are just as amazing as they've been for semiconductors.

The irritating part of all this is that we shouldn't have to rely on data filched from a French retailer to know what to expect from our expensive flash drives. The vendors know what the reliability is: they build hundreds of millions of devices a year and they track the returns on every batch.

But, like every other storage vendor, they would rather give us bland assurances than hard facts. First mover disadvantage and all that.

Bottom line: don't trust your SSD any more than you trust a hard drive. Backup your data locally and online at least once a week.

Only you can protect your data.

Comments welcome, of course. I'm on my 2nd SSD-equipped notebook: a 13" 4/128 GB MacBook Air. I expect that larger, faster & cheaper mini-SATA replacement drives will be available by the end of 2011.

Topics: Processors, Hardware, Networking, Storage

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  • RE: SSD reliability lower than disks?

    Sure, if you buy cheap junk. True with anything.
  • My experiance with SSD

    I am on my 3rd SSD. The first two failed completely within 3 months of being installed in my laptop. After the second one failed I was able to attribute the failure to a hot undock event from the docking station. This had never been a problem with rotating disk drive. I have since disabled the hot undock option in the bios and make sure the system is in standby before I undock it.

    The 3rd drive sat on the shelf for almost 6 months before I installed it, because I didn?t want to go through the hassle of rebuilding my laptop if the SSD failed. Again. I finally purchased an imaging backup package and an external hard drive to keep a daily restorable backup.

    I love the performance increase. My 3 year old C2D is faster than the new i5s I have purchased recently because of the SSD. But because of my experience, there is no way I would ever deploy an SSD on one of my users laptops. I just can?t trust them.
    • RE: SSD reliability lower than disks?


      I doubt those two deaths were from anything other than you getting two bad drives (it happens). At to the 'hot swap' thing.... YOU ARE NOT SUPPOSED TO HOT SWAP A SSD DRIVE!

      Says right on their websites that doing that can kill a SSD drive instantly.
  • SSD unreliability is not NEWS?

    I guess the Spin Doctors specialize in making us forget that!
  • When (not where) were the SSD's (in this study) manufactured?

    Perhaps this study details reliability results from "first gen SSD" hardware. That is to say, as Robin points out in his blog, all manufactured tech increase in reliability as manufactures gain experience building these devices.

    Another way of stating that, will this study accurately predict the reliability of Apple's current MacBook Air Flash storage systems over time? (I only use Apple products as an example because it was stated that this French retailer specialized in Apple products)
  • How does a capacitor ....

    boost voltage?
    • RE: SSD reliability lower than disks?

      charge in parallel, discharge in series? You would need more than one.
    • RE: SSD reliability lower than disks?

      @Economister see pmcgrath. Yep, it is called a "charge pump" and it is a technique used to multiply DC voltage. With care it can be made fairly efficient too. The problem is that typically you do it in powers of 2 and as that power increases the efficiency drops. As was stated in another post you charge a bunch of caps in parallel and then connect them in series for the discharge. You need an oscillator to throw the switches quickly.
      • RE: SSD reliability lower than disks?

        @DevGuy_z What happens is the incoming DC is converted to AC through the oscillator. this is then fed into on-chip voltage multipliers made with capacitors and diodes string in such a way that the voltage builds up. Google "Voltage Doubler." which uses AC as an input.
      • RE: SSD reliability lower than disks?

        @ DaemonSlayer

        Some DC to DC Voltage doublers work this way, but not this one. Basically, capacitors are charged in parallel, then discharged (generally into other capacitors) in series.

        With two capacitors, it nearly doubles the Voltage, but one can use more than two capacitors.

        A problem can occur if you need a lot of current. It is hard to do, at which point you actually need the oscillator and transformer, followed by a diode bridge to turn it back to DC.
  • RE: SSD reliability lower than disks?

    In addition to the conditions listed by previous posters here, a good chunk of the failures could also be caused by the limited amount of write cycles that flash and SSDs can handle. The "major players" in operating system software all use temporary files. There is the potential of opening large numbers of temporary files just by booting up the operating system. This is not to mention all the software installs/uninstalls that go on, application temporary files and the temporary files used by browsers. Hundreds, even thousands, of temporary files and their respective write cycles are happening. Most of these operating systems by default do not take into account being installed on a limited write cycle drive. Thus, in their default configurations, all of these write cycles are happening on the SSD. The more write cycles, especially in or near the same storage locations on the SSD, the quicker the failure.

    I have a Toshiba laptop with both an SSD (boot drive) and a regular hard drive. Out of the box, the system was not installed or configured with consideration for the SSD. I have scoured the system looking for any and all references to temporary locations and files. Every one of them that I have found have been changed to use the regular hard drive for temporary storage.
    • RE: SSD reliability lower than disks?

      @mrye@... IF your SSD has a small capacity, what they probably did was install the OS on the SSD, and then configured Windows to use traditional HDD storage for everything else. Better watch how far back you keep for your System Restore points, unless that was defaults/switched over as well.
  • RE: SSD reliability lower than disks?

    Robin, what kind of flash tech did they test? MLC will only last 100,000 writes where as SLC will go to 2-5 million writes. The SLCs are used in military application and are more money and are extremely fast like 250MB/s. They also have smaller capacities and promise to bring out larger drives in the future.
    • The good ones also tend to be quadruple the price

      And at $1,000 per SLC SSD, this is unobtainable for most people.<br><br>Besides, what will you do if the SSD outlasts the controller?
      search &amp; destroy
      • Maybe, but were the SLCs checked for reliability?

        @search & destroy

        No sense putting in unreliable disks for any price for the data is more valuable than the drive. If the SLCs were ramped up in production the price would drop from $11.50 per gigabyte. Since they use these in the military, they can take plenty of punishment. As for the controller, that is on the motherboard or a daughter card. Separate piece. Just take the drive off and hook it up to another computer with a USB adapter and get your data. You also have to backup to more than one disk.
      • RE: SSD reliability lower than disks?

        I think he means the flash memory controller built into the SSD itself.

        I do agree that if they ramped up production, SLC prices would fall. But I suspect that's not the industries intention since they want people to buy cheaper MLC drives every two or three years instead of the more expensive SLC drives every ten years.
      • RE: SSD reliability lower than disks?


        I believe the memory controller in the SLC is better too.

        I have valuable data so I would go with the SLC. I can juggle so many and 2 or 3 SLC would probably cheaper than 5 or 6 MLC to guarantee against data loss. The trick is to have a few hard drives going at once to prevent data loss.
  • Wrong measure of reliability

    Retail return rates aren't a measure of product reliability. The #1 cause of return is buyers remorse, not product failure or product quality. The #2 cause is "I don't know how to install this", which also doesn't have to do with reliability.
  • Don't trust anything

    Power pumps are also known as Joule Thieves, and are turning up in LED torches that only need a single AA or AAA cell to run them rather than the traditional 3 cells (which always left 1 spare in a 4-pack). In fact you can put a cell that is dead in a normal torch into a power pumped LED torch and get another hour or two of light.
    Re the reliability of drives, don't rely on any of them. Even if someone developed a storage that could last a thousand years with 100% reliability, it's useless if someone steals it or you have a house fire. Personally a 2TB drive terrifies me. 2TB is a helluva lot of data to lose and if the data is genuinely valuable you should regard the minimum backup as 2x the capacity in 2 different locations. My MacBook Pro backs up to an off-site(ish) RAID via Time Machine and to a weekly SuperDuper clone.
  • Retail info reliable

    Unsure how you can assume things just from one retailer - when a single store or multiple. From what it looks like, the retailer lumped all the bad SSD disk together even though it's theoretical that the bad disks could of come primarily from one company. [Sort of like saying that if a politician is corrupt then they all are - well THAt could be true.]

    If there was some type of broad study which lists the reliability of SSD drives from all manufacturers and compare against the PATA/SATA drives, then that would be different.

    In the end, [at least part of] this blog is nothing but shotty reporting.
    Gis Bun