Black magic speed test 50MBPS???

Discussion in 'MacBook' started by BNHabs, May 1, 2015.

  1. BNHabs, May 1, 2015
    Last edited: May 1, 2015

    BNHabs macrumors regular

    Joined:
    Jul 5, 2010
    #1
    My write speed varies all over the place and the arrow moves up and down erratically?

    Is this an issue with the SSD?

    Mine seems to get 500MB write and 700MB read but sometimes it only gets half of that for each one and the spedomitar seems to be very erratic and it jumps up and down.

    It seems to be that only the write speeds are very erratic and they jump up and down during the speed test.
     
  2. Alekto macrumors regular

    Joined:
    Nov 15, 2012
    Location:
    Tokyo
    #2
    The test just does that. Eventually it'll settle on a final number.

    That's all you have to worry about.
     
  3. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #3
    Okay but my write speeds them to be very erratic: it'll go to 500mb in same test but then slow down to 400 or even 300.

    The speedometer sometimes goes up and down erratically whereas the read speeds are always smooth and consistent.
     
  4. Alekto macrumors regular

    Joined:
    Nov 15, 2012
    Location:
    Tokyo
    #4
    When you say it's erratic do you mean it's giving you different figures at the end of each test or do you mean it's giving you different figures while it's actually running? If it's the latter, that's normal behaviour.
     
  5. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #5
    Different figures while running. It'll go to 500mb but then slow down to 400. Or it'll go to 400 and slow down to 300 during the write speed test (same test).
     
  6. Alekto macrumors regular

    Joined:
    Nov 15, 2012
    Location:
    Tokyo
    #6
    OK then its normal behaviour and nothing to worry about. As I said, the only thing to concern yourself with is the final number.
     
  7. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #7
    My final number is different each time though? Sometimes I get 500 write sometimes 300.

    The write meter jumps up and down and is not smooth in going up like the read is.
     
  8. Alekto macrumors regular

    Joined:
    Nov 15, 2012
    Location:
    Tokyo
    #8
    Then I'm stumped mate. Sorry, maybe someone else has a better explanation than me.
     
  9. hans1972 macrumors regular

    Joined:
    Apr 5, 2010
    #9
    Also you should look at random reads and random writes. Normal workloads on a computer is much more random than they are sequential.
     
  10. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #10
    Does this point to my SSD being defective?

    The write tests just seem inconsistent and the speed randomly drops and goes higher erratically.
     
  11. legioxi macrumors 6502a

    Joined:
    Mar 2, 2013
    #11
    Unless you're experiencing an actual issue with your laptop, no.
     
  12. Freyqq macrumors 601

    Joined:
    Dec 13, 2004
    #12
    That's just how that test is designed. It's the test, not the SSD. Most tests do the test in the background and give you the final score at the end.
     
  13. BrandonPrice31 macrumors member

    Joined:
    Dec 16, 2014
    #13

    No but the speedometer will go to 500 and just drop down to 300 or 400 in the same test. I'm not talking about scoring 500 then next test scoring 400.

    Is what I described still normal?

    ----------


    I've watched videos of people using the same test online and theirs don't do that?
     
  14. Freyqq macrumors 601

    Joined:
    Dec 13, 2004
    #14
    The final score is the only one that matters. Also, the test is best done with nothing else open and no background tasks whatsoever. Any task going on other than the test affects the test score. This could even be spotlight indexing, which you can't even know is occurring otherwise.

    Anyway, that particular test is just designed just to give you an idea what your SSD speed is for their particular brand of products. The one the SSD manufacturers use is ATTO and they run it on a PC with nothing installed.
     
  15. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #15
    I have nothing running in background.

    My worry is that the write speed (in the SAME on-going test) will reach 450 write but then just drop to 300 and end up at 350. Their are times I've hit 475 end result but the whole thing for write is erratic. I'm going to do a video for you guys so you can tell me.
     
  16. Freyqq macrumors 601

    Joined:
    Dec 13, 2004
    #17
    Every time you run it, you do 5 GB of writes. Eventually, it is going to slow down until TRIM and garbage collection clean the drive in the background. That test is suppose to be run very occasionally lol. If you were running it on a completely clean drive and ran 3 runs of the test from a boot drive that only ran that one test, maybe you'd get closely consistent results. Your drive is fine.
     
  17. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #18
    I posted videos using Taptalk on my phone with other account.

    See how the write speeds go up and fall and are all over the place? My reads don't do that.
     
  18. Freyqq macrumors 601

    Joined:
    Dec 13, 2004
    #19
    lol! Mine does exactly the same thing. 15" rmbp late 2013 with 512GB PCIe SSD. Read my above comment on how trim and garbage collection work for writes on an SSD.
     
  19. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #20
    It's being doing this since the first test.

    Watch the video - that's fine?

    It ran like this on my first test I did with the program. Keep in mind this laptop is brand new. Why don't the review videos do that?
     
  20. Freyqq macrumors 601

    Joined:
    Dec 13, 2004
    #21
    Well, mine does it too. It's fine. I've had this thing since October 2013, and the SSD has been fine this whole time. If you want the professional level of result, install ATTO on a bootcamp partition and do 3 runs of that. Manually run trim before each run.

    Also, due to the nature of how SSDs work, speed goes down over time. So, every time you run that test, you age the SSD. The SSD manufacturers design them expecting about 20GB of writes a day. That's really hard to do with usual operations, but that test does 5GB in a few seconds...
     
  21. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #22
    I ran this test for the first time and the same thing happened - even that is normal?
     
  22. theSeb macrumors 604

    theSeb

    Joined:
    Aug 10, 2010
    Location:
    Poole, England
    #23
    I watched your video and it's perfectly normal in terms of how the Blackmagic benchmark works. The important numbers are on the right side. Edit: I've just realised that you posted the same video in two threads, so this is a duplicate. My apologies.
     
  23. newellj macrumors 603

    Joined:
    Oct 15, 2014
    Location:
    Boston, MA, US
    #24
    This is totally normal with the BM test.

    ----------

    Absolutely not, no it does not.
     
  24. BNHabs thread starter macrumors regular

    Joined:
    Jul 5, 2010
    #25
    Watch my video though in this thread, my write will go to 500MB and then drop to 300 in the same test.

    Does yours do that? Watch both videos.
     

Share This Page