Mac Mini Samung 840 Pro SSD

Discussion in 'Mac mini' started by djbetterly, Aug 5, 2014.

  1. djbetterly macrumors newbie

    Jan 4, 2005
    So I have a mac mini (2.6GHz i7 - 16GB Ram) that I put a samung 840 pro SSD into. I am continuously running into what seems like trim problems.

    I've been using the Diglloyd Tools to test. I ran disk tester a week ago on the drive bare (after cloning to second internal) and the first iteration came up at about 40MB/s, after about 4 iterations I was back up to almost 400MB/s.

    Now just a week later, I'm back down to 40MB/s again. I'm not sure I understand why this is happening so fast. I'm an avid photoshop user but I don't use my boot as my scratch. Just trying to figure this out.

    Any advice is welcome.

  2. realuseless macrumors newbie

    Aug 6, 2014
    Not sure if you are aware but Apple disables TRIM on non-apple SSDs. So if you haven't enabled it manually then that might be your issue.

    You can either check the hackintosh community for trim enablers or if you feel confident with the terminal you can run the commands yourself:
  3. drsox macrumors 65816


    Apr 29, 2011
    Try this :
    or this :
  4. brdeveloper macrumors 68020


    Apr 21, 2010
    Never had problems without enabling TRIM on both my 840 EVO (I know it's a totally different technology than 840 Pro, though) and my Crucial M500. If you have TRIM enabled, try disabling to see what happens.

    I think that "if you have ~350MB/s without TRIM, don't enable TRIM".
  5. MarcelEdward macrumors member

    Sep 24, 2012
    I had to enable trim through the terminal to get it to work.

    You should enable it ... I find it strange that osx does not enable it automatic with ssd.
  6. ColdCase, Aug 8, 2014
    Last edited: Aug 8, 2014

    ColdCase macrumors 68030

    Feb 10, 2008
    If you write and delete a lot of data, trim will help your performance. When the OS writes to a location on the SSD that already has data, the SSD must first erase the entire page and then write the data. If the location is empty or previously erased it is significantly faster (no erase of moves). Its more complicated, however. SSDs have sophisticated algorithms that speed things up, like moving the entire page to a new empty physical location and updating the virtual maps. But there often comes a point where the overhead just slow writes to a relative crawl. Trim commands tell the SSD which virtual memory locations have been deleted (or is no longer in use) so it can erase the physical memory in preparation for quick reuse and more efficiently manage the physical memory chips.

    If all you are doing is reading data from a SSD, trim has no effect.

    So whether trim is noticeable or not, depends on your use case. Trim is a relatively new, SSDs for years have been used without it. Most casual users will not notice. SSDs don't allocate their entire physical memory to the OS, keeping some in reserve. The SSD will use this spare capacity to clean up physical memory over time.
  7. RCAFBrat macrumors 6502

    Jul 10, 2013
    Montreal, QC

    Nice explanation.

    Makes me wonder if the OP doesn't have an issue completely unrelated to Trim (actually I've been wondering that since his or her first post)?

  8. ColdCase, Aug 8, 2014
    Last edited: Aug 8, 2014

    ColdCase macrumors 68030

    Feb 10, 2008
    Yes, I was thinking the same thing. Just how full is the drive? It may just be a bad drive. Running a disk tester over and over again will add wear and tear to a SSD (those gates just have so much life).

    On the other hand, that tester seems to run like any other app, so other apps and processes running on the mac that takes processing power may slow that tester down. What kind of processes are running when there are slow downs that are not running when things are going well (spotlight, TM backups....) ? . I dunno, just throwing out ideas.

    I used to test SSDs for a living and the first thing we looked at when we saw something strange like this, was what the host and Host OSs were doing.

    In my experience, if relevant, intermittent slowing to a crawl or simply crashing (corrupting) usually turned out to be a faulty drive, sometimes a faulty connection, unless one bumped into one of the drive's throttling thresholds.

    Double check the mini's internal SATA connections?

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