Power-hungry SSDs: Hotter than disks

Power-hungry SSDs: Hotter than disks

Summary: Making flash SSDs look like disks isn't easy. In fact, advanced high-performance SSDs use more power and run much hotter than disks. They aren't your father's thumb drive.

TOPICS: Storage, Hardware

Anyone looking at how flash SSDs have revolutionized mobile computing could be forgiven for thinking that all SSDs run cool and sip power. But they don't.

Flash technology isn't ideal for high performance apps. Each flash die has limited bandwidth. Writes are slow. Wear must be leveled. ECC is required. DRAM buffers smooth out data flows. Controllers run code to manage all the tricks required to make an EEPROM look like a disk, only faster.

Special Feature

Storage: Fear, Loss, and Innovation in 2014

Storage: Fear, Loss, and Innovation in 2014

The rise of big data and the demand for real-time information is putting more pressure than ever on enterprise storage. We look at the technologies that enterprises are using to keep up, from SSDs to storage virtualization to network and data center transformation.

So the number of chips and channels in high performance SSDs has risen to achieve high bandwidth and low latency. Which takes power and creates heat.

The price of performance

In a recent Usenix HotStorage '14 paper, Power, Energy and Thermal Considerations in SSD-Based I/O Acceleration, researchers Jie Zhang, Mustafa Shihab and Myoungsoo Jung of UT Dallas examined high-end SSDs, those with multiple channels, cores and flash chips. Fast, robust SSDs need all the help they can get. 

They found that high-performance SSDs exhibit characteristics uncommon in lesser SSDs.

  • High power. 2-7x the power, 282% higher for reads, up to 18w total.
  • High temperatures. 150-210% higher than conventional SSDs, up to 182F.
  • Performance throttling. At 180F the many-resource SSD throttles performance by 16%, equivalent to hitting the write cliff.
  • Large write penalty. Writes at 64KB and above in aged devices caused the highest temperatures, likely due to extra garbage collection and wear leveling overhead.

Performance throttling was not limited to the high-end SSDs. A mid-range drive slowed down at 170F, probably due to thermally-induced malfunction as the drive had no autonomic power adjustment.

The Storage Bits take

I found these results a little hard to believe, so I looked at some high-end enterprise SSD specs. Sure enough, I found an Intel SSD spec'd at 25w - twice the power required for a 15,000 rpm enterprise disk - and higher than any the researchers tested.

Should enthusiasts be concerned? Maybe. The performance throttling from high temps of even mid-range SSDs could affect a game at its most intense. If your system gets sketchy at high temps, this could be a cause.

For enterprise users this is a reminder to check specs and understand power and cooling requirements for high density SSD installations. Free-cooled datacenters may also be at risk for SSD-induced slowdowns.

While not a huge problem for most people today, the insatiable demand for performance will move more of the market to these high-performance SSDs. The time to think about the impact is now.

Comments welcome, of course.  Have you noticed any heat or power issues in your SSDs? 

Topics: Storage, Hardware

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  • Apples to apples

    But what is the heat compared to work cycles?
    If the SSD has 10x the bandwidth but less than 10x the heat, you're already ahead of the game.
    Since the heyday of overclocking there has always been a compromise. Low price, high performance, low heat. You can have any two (if you're really lucky)

    In your case, low price AND low heat have been sacrificed in the name of pure performance. The next step will be either the next smaller gate technology or slapping on a heat sink (some older 15k disks had them)
  • Irrelevant to most use cases.

    The IOPS per Watt of SSDs is exponentially higher than any HDD, so the power output is expected. Sure, a Datacenter PCIe SSD requires 25W for operation, but it outperforms hundreds of HDDs, the comparison is not even close.
    No computer user in operating system usage, and even in heavy usage, will ever see the type of sustained workloads that would reach these conditions.
    SSDs serve I/O requests faster than HDDs, so the QD does not build up. Low QD performance is the norm, it rarely, if ever, gets over QD3.
  • Right tool for the job

    It always comes down to right tool for the job. SSD - low storage, high IOPS, high power; Hard Drives - Large storage, medium IOPS, lower power; Tape Array - very large storage, low IOPS, flat power consumption with storage size.
    Buster Friendly
  • And one more thing...shouldn't they cool the device?

    Another issue with these obviously flawed tests is the lack of cooling. All enterprise SSDs have stated airflow parameters, typically 200-300LM. None of these SSDs were cooled according to the guidelines, or cooled at all, period.
    Running your vehicle without oil will also cause it to overheat, and is very close to the method used to 'test' the temperature of the SSDs. I smell a 'study' funded by a group with a competing type of product.
    • That won't matter

      Having heat buildup wouldn't make any difference. All we care about in this case is energy flow rate.
      Buster Friendly
      • Yes, it does matter.

        Of course heat buildup matters, especially with the conclusion that SSDs run at high temperatures and throttle. Not taking cooling into consideration is asinine.
        • It doesn't

          The heating is equal to the energy going into it. That's physics. Cooling only serves to pump that energy back out. All we care about is the wattage and that tells us everything else.
          Buster Friendly
          • Seriously?

            So you suggest testing a product outside of its design, and then claiming it doesnt work? If you dont cool it as recommended, yes it will overheat.
          • Irrelevent

            That's irrelevant to the claims made in the article. Look at this way. You have a toaster running in your kitchen and your house is 70 degrees. Now you run the same toaster for the same amount of time but your house is 80 degrees. Does the power usage of the toaster change? While an SSD is much more complex the same basic laws of physics apply. Energy in = energy out. What you do with that energy after it leaves the device is irrelevant to how much heat it created. That's what we're referring to in how hot a device runs.
            Buster Friendly
  • Hybrid Storage for the win?

    I think the ultimate answer would be to utilize hybrid storage for the victory. Use the SSD caching for your reads and then contain your Hard drives as a RAID storage setup for your storage. Depending on the controller for your SAN, this should drop the workload considerably and lengthen out the life of the SSDs even longer.
    • More generally

      More generally a Hierarchical Storage Management (HSM) system that migrates files between storage resources based on usage. The first one of those I did was mid-90s. Files can even be migrated into a tape silo and fetched automatically when someone accesses them. To the end user it looks like a simple filesystem even though the files may be spread over many different systems.
      Buster Friendly
    • Hybrid

      Don't hybrid drives work harder and generate more heat than conventional stand alone SSD's? Lots of complaints about Seagate's Momentus drives getting way hot in reviews. A stand alone SSD just reads and writes when info is requested. A hybrid drive is determining which files/apps are used most frequently and moving that info on and off the SSD as needed.

      A lot of people complaining that their Boot times did not increase until they shut down 3 or 4 times. Granted, the operating system isn't going to be moved very often, if ever again, but the idea here is still relevant. With hybrid drives there's significantly more I/O than wih a standard drive.
  • Not for me (less heat with SSD)

    I use the laptop (HP 8540w) the same way since I replaced the HD with an SSD (Crucial M500 240 GB). I have noticed the less heat out of the vents, this not a real scientific measurement but is nevertheless perceivable. Which I guess, confirm the explanation of the comments above (SSD offers more IOPS per watt).

    Of course, other SSD benefits are clearly obvious: less noise and MUCH faster disk I/O. I hated this laptop before, now it is very usable.
    • More Info Please

      Thank you. Any feel for how the SSD effected battery life on your HP? Obviously Laptop use is not the same as Enterprise level use, but there are many who would find an SSD upgrade solves many issues on our lowly Laptops...
    • less heat, less power

      Why would Apple and Sony (and others) be switching all of their power sipping computers to SSD if it wasn't better for the battery life? CNET is rating the Macbook Air at 14 hours. A traditional harddrive would be spinning up and down constantly just trying to save the power and would never come close to the savings of an SSD.
      Bryce Steiner
    • That is true

      That is true as the laptop is pretty much the ideal application for an SSD. This is a result of a small duty cycle and the faster time the SSD can drop to idle. Hard drives have a spin up time so you don't want to spin it down until more idle has passed. It also benefits from being more resilient to movement as there's no moving parts to get knocked around. In this article they're talking about performance applications which it runs at maximum capacity almost all the time.
      Buster Friendly
  • SSDs are nice, but...

    SSDs may be lighter, more reliable under low load and more resistant to shock (I believe this is why Apple likes them). As for making things really faster, I have doubts. Hybrid HDDs demonstrate that after buffering the essentials it does not matter how fast you access the rest of the data, and the cheapest and smartest way to do that is to add RAM, not an SSD. This is valid even for Windows, and plain evident for anything with a sane OS, say a Mac.
    • SSD's are much faster

      >>As for making things really faster, I have doubts.
      They really are MUCH faster. I replaced the harddrive in my iMacs and it improved the speed tremendously. I've updated RAM and 5400 to 7200 harddrives in the past and I've never had better performance improvements than SSD's. It's like adding RAM since your harddrive is used as virtual memory even on a 24 GB system.
      Windows benefits just as much.
      From a cold start it's now 10-12 seconds vs 40-50 seconds.
      Bryce Steiner
      • They're fast in some cases

        They tend to be faster in small randomly scattered reads but not necessarily in large sequential reads. Since a single user system tends to be a lot of random reads along with a lot of idle time, the SSD works great. It's all about how you use it.
        Buster Friendly
    • A bit simplistic

      Yes RAM is better than a faster HDD to reduce paging with VM.

      Once you have more RAM and your system is not paging heavily then the drive speed for data access is a huge issue.

      An application loads from the drive at least once no matter how much RAM you have.