USB 3.0 External Hard Drive Slowing Down on iMac...

Discussion in 'iMac' started by ghsNick, Dec 19, 2016.

  1. ghsNick, Dec 19, 2016
    Last edited: Dec 19, 2016

    ghsNick macrumors 68020

    ghsNick

    Joined:
    May 25, 2010
    #1
    Hi -

    I purchased this external hard Drive six months ago and noticed the speeds have slowed down a lot in the time I've had it. I've posted 3 speed test results (June, October, December) and you can see it's slowed down as I've filled it up. (From 180 MB/s to 110 MB/s)

    It's a 6TB drive and I'm wondering how to speed this up...or if it's stuck this way because I've filled up 5 out of the 6TB over the last six months.

    Any advice is appreciated! Thanks
     

    Attached Files:

  2. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #2
    Filling up a drive will slow it down. The way drives work, there are some areas that are faster than others, and if the data you've put on it occupies the faster lanes, new data will have to occupy slower lanes. If you free up the space you can use the faster lanes for different data again. There are also tools that move data around to get optimal performance for what you really use. Note however that even though the speed tests claim so, the drive isn't slower with all data. New data written will write slower and that data will read slower, but data already present on the faster lanes will read the same speed they always have. Assuming they don't have to be read right after data in a far away lane so the read-head has to move a lot.
     
  3. ghsNick thread starter macrumors 68020

    ghsNick

    Joined:
    May 25, 2010
    #3
    Thanks.

    When I first ran my test I only had about 1 TB of storage (hence the fast speeds), the second test had about 3TB of data and the latest test I ran has 5TB of data.

    I use this as my iTunes library since I have ALOT of movies on there (recently took all 300 Blu Rays I own and put them on the drive). Will these decreased speeds give me any issues while streaming to my Apple TV thru Home Sharing?

    I noticed buffering while watching the other night and I'm concerned it has to do with the drive slowing down.
     
  4. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #4
    The speeds should still be plenty fast for BluRays. Reading optical media from a disc (BluRay, DVD, CD, doesn't matter) is a whole lot slower than this anyway. The only way I see disk speeds being the cause of such a problem, is if they were very heavily fragmented, but I doubt that is the case really. It'd have to be very very fragmented, and just filling up a drive leads to pretty much no fragmentation (occurs when you delete data occupying one track, and replace it with data bigger than before, so the data for one file is placed several different places on the disk).

    With streaming, I wager it was just a hiccup in the wireless connection.
     

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