windows 8 - Strange SSD Response Time Spike

07
2014-07
  • ronag

    I have a Samsung 840 EVO 1 TB SSD disk.

    I am streaming data to this sequentially at a rate of 60 MB/s to four different files (15MB/s each) with the size 168GB (preallocated) each in a circular manner (i.e. when it reaches the end of file it starts overwriting from the beginning). Each "stream" flushes data to its file in batches of 32 MB (though I don't think this matters due to Write Caching and RAPID mode).

    This works fine for a little while. However, after a while the "Average Response Time" (as seen in the Windows Task Manager) spikes up to 20000ms and my streaming application is forced to buffer data into memory until it runs out and crashes. The spike occurs after writing around 16GB of data in total.

    What could cause such spikes and how do I avoid it?

    I am using the recommended settings by Samsung for "Maximum Reliability".

    • The drive is over provisioned by 25%.
    • AHCI is enabled.
    • Write Cache Buffer is enabled.
    • Write Cache Buffer Flushing is disabled.
    • RAPID mode is enabled.
    • Windows 8.1.

    The exact same usage scenario works fine on a high end spinning drive.

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    Related Question

    hard drive - Performance SAS vs SSD
  • Questioner

    When it comes to speed of development, a very important thing is your hardware. I need suggestions to help me choose between hard drives. What is the best solution?


    • Related Answers
  • Seasoned Advice (cooking)

    Asking whether SAS is better than SSD is like asking whether IDE is better than a tape drive.

    SAS is a drive interface, like SCSI, IDE or SATA. SSD is a drive technology, like CD, DVD or Hard drive.

    Just as you can get Hard Drives with any of the above interfaces, you can get SSD's with different interfaces too.

    So, ignoring the question title - as with many questions like this, the answer is 'it depends'.

    Normally when people compare the performance of storage media, they look at the headline 'throughput', Megabytes per second, but this is only really valid when doing large block reads and writes. For software development, where the number of different, often small, files which need to be read and written to compile an application is quite large, the number of I/O operations per second can be much better indicator of overall performance. As such, I tend to assume that software development fits uder the "Workstation performance" model.

    So when I research the best options for new hardware, I tend to go to Tom's Hardware and look at the workstation benchmarks. For instance the new VelociRaptors are head and shoulders over typical 7200rpm SATA hard drives, but even these figures pale into insignificant when you compare them to the top end SSD's.

    Ultimately though, it is up to you to determine whether the performance differences justify the extra costs.

    Edit: Just to add some fuel to the fire, if you are considering one of the cheaper SSD's out there, you might be ineterested to see these articles at Anandtech and PC perspective. It might take you a while to read through them, but you will learn an immense amount about SSD's, what to look out for and what to avoid.