Does the slower read/write speed of the 256 GB SSD make a difference in performance?

Discussion in 'MacBook Pro' started by Hieveryone, Apr 20, 2014.

  1. Hieveryone macrumors 68020

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    #1
    I recently bought a MBPr 13" with a 2.6 GHz processor and 8 GB RAM.

    I went with the 256 GB SSD, and I get a read speed of 730 mbps and a write speed of 585 mbps using the BlackMagic Disk Speed app.

    Would I have noticed any difference in speed if I had gotten the 512 GB SSD, and am I bottle necked because I got the 256 SSD?

    Thanks.
    --------------------------------------

    EDIT: Also, what is primarily affected by the slower read/write speed?
     
  2. hirtaza macrumors member

    hirtaza

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    #2
    read speeds are 700 something for the top model as well and the write speed i believe are 700 but you shouldn't worry as all the apps that you open/close, safari showing the websites etc are all done by read speeds so if ur worrying the 512gb harddrive will load things faster or boot up faster it will be the same since 256gb and 512gb's both read speeds are 700 something...hope this helps
     
  3. Hieveryone, Apr 20, 2014
    Last edited: Apr 20, 2014

    Hieveryone thread starter macrumors 68020

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    #3
    So what exactly will the write speeds affect? I understand it's if you want to "write" something to the disk but can you give real world examples? Like "opening iMessage" etc.

    Thanks!

    --------------------------------------------

    I looked it up. It basically said write speed affects how long it takes to save something.

    So I'm guessing if you are doing a paper on Horticulture and want to save it, that's where the write speed comes in.
     
  4. yjchua95 macrumors 604

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    #4
    In real life usage, you wouldn't find any difference unless you're doing I/O intensive tasks.

    Your speeds are of the SD0256F variety (SanDisk). On my iMac, I have a 256GB SSD, but of the Samsung SM0256F variant. The Samsung variant performs at 720MB/s read and 670MB/s write, which is way faster than the SD0256F.

    Also, random read/write performance on the Samsung variant is also better.

    Between the SM0256F and SM0512F, there's barely any difference. Between the SD0256F and SM0256F/SM0512F there's a noticeable difference in I/O intensive tasks, and also maybe a 3 second slower boot up time.
     
  5. hirtaza macrumors member

    hirtaza

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    #5
    exactly thats what i was going to write i have a perfect video for you explaining the difference between write and read speeds but im at school studying for my final tomorrow at 9am i will link the video tonight or tomorrow for your convenience however just an overview i believe write speeds would be how faster you can save a file (movie or maybe smaller) from one partition to another im sorry for now but yea i ll definitely help you with it tomorrow
     
  6. Hieveryone thread starter macrumors 68020

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    #6
    Excuse my ignorance but what does I/O mean?

    And I'm just glad it makes no difference in real world use. The read speeds are the same and I save everything to an external drive anyway...so I'm guessing I"ll never ever see the difference...(I hope).
     
  7. simon48 macrumors 65816

    simon48

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    #7
    Input-Output. So "I/O intensive tasks" means tasks that have intensive reading and/or writing to/from the disk.
     
  8. Weaselboy Moderator

    Weaselboy

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    #8
    You will never notice a difference in day to day usage. Now if you were editing a 20GB video in Final Cut and timed the save with a stopwatch, you might notice a small difference. But other than a very write intensive activity like that, you cannot tell.
     
  9. Hieveryone thread starter macrumors 68020

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    #9
    Hi guys.

    My friend let me borrow his MacBook to make a comparison video. I made sure to turn off all background applications, launch items, etc. They are both using around 3GB of RAM at startup to make things fair.

    On the right side you have a 13" 2.6 GHz, 8 GB RAM, 256 SanDisk SSD

    On the left you have a 13" 2.6 GHz, 8 GB RAM, 512 Samsung SSD

    https://www.youtube.com/watch?v=--OETfleNJM&feature=youtu.be

    As you can see, opening applications is EXACTLY the same speed.
     
  10. Hieveryone thread starter macrumors 68020

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    #10
    Were you still going to post the video? Please.
     
  11. yjchua95 macrumors 604

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    #11
    To save him the trouble of posting the video, I'll try to explain it here. Correct me if I'm wrong.

    So let's say you're working on a 80GB 4K video and you want to export the project from FCP X to your hard drive.

    80x1024 = 81920MB.

    Write speed (SD0256F): 550MB/s.
    Write speed (SM0256F): 670MB/s.
    Write speed (SM0512F): 720MB/s.
    Write speed (SM1024F): 970MB/s.

    Time taken to export video, assuming that full write speeds are attained (in practice, this is practically impossible due to the throughput from other processes in the background):
    SD0256F: 2 mins 29 s.
    SM0256F: 2 mins 3 s.
    SM0512F: 1 min 54 s.
    SM1024F: 1 min 24 s.

    However, for more realistic read/write speeds (depending on the type of video you're looking at - see right side of attached screenshots), it's going to be far slower as the processor needs to encode and output it.

    Top left: SM0512F
    Top right: SM1024F
    Bottom left: SM0256F
     

    Attached Files:

  12. Hieveryone thread starter macrumors 68020

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    #12
    Thanks for the explanation. It was very clear. It doesn't seem to bad of a difference. only 20 seconds more or so.

    Did you see the video I uploaded? It shows that they're about the same for regular use.
     
  13. yjchua95, Apr 23, 2014
    Last edited: Apr 23, 2014

    yjchua95 macrumors 604

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    #13
    I did.

    However, the 20 second difference is assuming that the full speeds of the SSD are attained, which is impossible in practice because of background processes taking up operations in the SSD and also may be limited by the processor in hyper threaded tasks (e.g. video editing and exporting it).

    For the actual speeds, refer to the right side panel in each BlackMagic screenshot.

    For instance, if you're doing 12-bit RGB 4:4:4 at 1920x1080, the write/read speeds on a SM0512F will only be 60MB/s and 61MB/s respectively, and 52MB/s and 60MB/s on a SM0256F respectively.

    This means that an 80GB 12-bit 4:4:4 1920x1080 video will take 22mins 45 secs to export on an SM0512F and 30 mins 18 secs to export on a SM0256F. It'll be slower still on a SD0256F.

    On a side note, the SM1024F is nuts and way faster at 172MB/s (both read and write) 12-bit 4:4:4 1920x1080. So an 80GB 1920x1080 12-bit 4:4:4 video will only take 7 minutes 56 seconds.

    Your values will vary because video encoding will be affected by the processor too. I tested this on a 2.8GHz i7-4558U (2 cores/4 threads), 2.6GHz i7-4960HQ (4 cores/8 threads) and a 3.1GHz i7-4770S (4 cores/8 threads).
     
  14. thundersteele macrumors 68030

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    #14
    Do you know why there are minus signs in the 1TB screenshot? Also some of the rates look suspiciously high... doubling the bare write/read speeds in some cases for the 1 TB drive. Are you sure those numbers are reliable? Is this something one can expect with the 1 TB drive for some reason (i.e. more buses etc)?
     
  15. Hieveryone thread starter macrumors 68020

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    #15

    I see. That's really good to know. I got the 2.6 GHz, 8 GB RAM, 256 SanDisk SSD.

    Is my computer still faster than a 2.4 GHz, 8 GB RAM, 256 SAMSUNG SSD computer?

    Or am I getting bottle necked b/c I got the SanDisk SSD, so the .2 extra GHz is pointless?
     
  16. yjchua95 macrumors 604

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    #16
    The 1TB SSD uses a 4-lane PCIe channel, while the 512GB SSD and smaller ones use a 2-lane PCIe channel. So the 1TB ones have double the throughput of 2-lane ones.

    ----------

    Nope, because:
    1. Your SSD is limiting you.
    2. The extra 0.2GHz is too insignificant of a difference, to the point that the SM0256F will be faster instead when exporting videos.
     
  17. Hieveryone thread starter macrumors 68020

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    #17

    Is there any benefit at all for .2 extra? Web Browsing? Something? It must benefit me in some way even though I have the SanDisk SSD...
     
  18. qawsed macrumors regular

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    #18
    My goodness man, enjoy your Mac and stop thinking about .2Ghz and theoretical SSD speeds. You have a really great machine, better than the majority of laptops out there. You'll drive yourself mad thinking about minuscule differences in performance like that.
     
  19. yjchua95 macrumors 604

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    #19
    No, it will not benefit you in any way.

    The processor upgrade is the least value-for-money upgrade on a 13" rMBP, because all processors only have two cores and four threads.

    However, on the 15" rMBP, there's more benefits going from 2.0GHz to 2.6GHz, because it's a larger difference and besides, each processor has 4 cores and 8 threads.

    I went for the 512GB on my 13" (2.8GHz i7, 16GB RAM, 512GB SSD), because:
    1. I didn't want to play the SD/SM lottery
    2. The machine was paid for by my dad, and he maxed out everything for me, although his decision to max out the i7 wasn't a smart one. I did tell him that I found the 1TB SSD unnecessary (because my 15" rMBP already has a 1TB SSD).
     
  20. thundersteele macrumors 68030

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    #20

    Thanks, that makes sense.
    I feel that this is getting a bit one-sided here. It is not like the only purpose of the MBP is exporting videos. The 2.6 GHz version should be about 8% faster in compute intensive tasks.
    Most of the things I do for work are either compute intensive or not intensive at all. So the slower SSD speed of my SD256 is mostly negligible (doesn't mean I wouldn't prefer having the faster drive), while the faster CPU gives me a small benefit.

    Both the 256 GB SanDisk and the 2.4 GHz CPU are more than fast enough for everyday purposes. Whether someone benefits from a specific upgrade depends on what the intended use of the machine is. It that is just web browsing, video watching and some sort of Keynote or text-editing work it doesn't matter.

    The CPU upgrades on the 13'' are rarely worth it. If CPU power is really crucial, then a quad core is a much better choice. On the other hand 8% are 8%, and I will at least sometimes use it, while the SSD write speeds are mostly negligible for me.
     

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