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Need help understanding my HDD bottleneck

Discussion in 'Storage Drives' started by benjii, Jun 27, 2018.

  1. benjii


    Joined: Apr 26, 2013

    Posts: 3,229

    Location: Plymouth

    I have a 2TB USB 3.0 HDD connected to my HTPC. I've transferred a bunch of files back and fourth between my drives and know that its read and write speed is 108MB/s. However, when downloading five, 11GB files from my FTP server at a combined speed of 47MB/s, the write load reaches 100%.

    Moreover, when I attempt to watch a video file from that drive, while downloading the aforementioned, it stutters and can't playback as the read load is also at 100%. The video file is only 45Mbps, that gives it an equivalent read speed of 5.6MB/s, well short of the 108MB/s it's capable of. If I stop the downloads, however, the video file plays back flawlessly and the read load is only 18%.

    CPU and RAM usage while doing all of the above is fine and nowhere near bottlenecking. It's obvious there's a HDD bottleneck here. but I don't understand what is causing it. Does anyone have any ideas or tests I can do to route out the problem?

    The drive is a Toshiba HDTB320EK3CA, 5400rpm, 16mb cache (I think, hard to find info).

    Any help would be greatly appreciated.
    Last edited: Jun 27, 2018
  2. Journey


    Joined: Oct 18, 2002

    Posts: 4,666

    Location: West Midlands

    It's just trying to do too many seeks, and read/writes at the same time. Can you imagine, you trying to read different words from different parts of a book, and the same time as trying to write in the same book? Sequential write speeds will always be higher when no other operations are taking place on the HDD, mechanical drives are not great for this, hence why the low latencies and access times, combined with fast transfer rates make SSD's such a large upgrade.