Why SSDs don’t perform

“SSDs are a new and evolving (and the SATA versions are already obsolete) technology,” Robin Harris reports for ZDNet. “It’s not surprising that we’re still learning how and where to use them.”

“One of the most popular uses of SSDs is in servers hosting virtual machines,” Harris reports. “The aggregated VMs create the I/O blender effect, which SSDs handle a lot better than disks do.”

Harris reports, “But they’re far from perfect, as a Usenix FAST 15 paper Towards SLO Complying SSDs Through OPS Isolation by Jaeho Kim and Donghee Lee of the University of Seoul and Sam H. Noh of Hongik University points [sic] out: ‘In this paper, we show through empirical evaluation that performance SLOs cannot be satisfied with current commercial SSDs.”‘

Much more in the full article here.

MacDailyNews Take: Yes, using an SSD poorly can waste most of its possible performance, but to say they “don’t perform,” as Harris’ headline states, is ludicrous.


  1. SLO, not San Luis Obispo, but Service Level Objectives.

    Would be nice to know without following 2 links.

    This issue is not likely to affect users of laptops and desktops unless they are writing and deleting a horrendous amount of data in real time.

    1. “This issue is not likely to affect users of laptops and desktops unless they are writing and deleting a horrendous amount of data in real time.”

      Which everyone under 20 is doing by torrenting 24/7 and streaming video. Then again, hardware is disposable to them right? Break and buy a new one….

      1. Many of us have been using SSDs as our main system volumes for years without these mysterious performance issues. Go figure! 😀

        I’ve got a three year old 480GB OWC Mercury Electra 6G SSD in my Mac Pro tower at the moment. I use this machine for all of my work, including software development, graphic arts, and general use. The SSD just clocked in at 382 MB/s read and 254 MB/s write speeds – and it’s three years old and TRIM has never been enabled.

        The fact is in general, even old SSDs are far faster than the hard drives they replaced, and most are still going strong.

          1. That is disturbing…OWC is one of my “go to” retailers for Mac-related components – drives, memory, etc.

            I have used an OWC external HDD for Time Machine for several years without any issues (which was not the case with the Maxtor HDD that it replaced).

            1. This may sound backwards, but my experience with SSD’s encourages me to consider my next Mac laptop to have a HDD (choices are limited). HDD’s can be more reliable because you are given a warning as they go bad. SSD’s don’t and they take your data with them.

              OWC is a good vendor except they have treated me poorly on this item. I will be contacting the Better Business Bureau for relief. BTW, OWC has 25+ complaints against them by the BBB).

            2. And for me, my experience is that today with any laptop, it is just a few minutes per day to run CCC to update a clone to an external HD/SSD so I don’t worry about any of the worst case scenarios.

  2. First rule of journalism: spell out initials on first reference. But today we get articles reporting “SSDs may PDQ if HDML and THIVP are not RB MO! In addition, KHNL. TSAQ PQSR!”

  3. Harris is a well known expert in this field, as opposed to the anonymous fanboys who run this site. They obviously didn’t understand the article, or didn’t even read it.

    It’s a well known problem with SSD’s. After a drive is filled up, it’s speed can decline for random IOPS by as much as an order of magnitude. This has been considered a serious problem. What has been found, and something I’ve verified for myself, it that drives can slow to 30MBs. That’s serious.

  4. ‘Don’t perform’ relative to WHAT? That’s the next question.

    I work on my MBP 15″ late 2013 with whipping fast SSD all day long. What’s the bottleneck in my system? I don’t know and I don’t notice! What exactly am I supposed to want now? Making my SSD faster would be great. So let’s simply get going there! Denigrating the old technology of the ‘now’ is always going to happen. So I have to point out that DUH! The future will be faster!!!

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