Mac Mini - USB 3.0 Bus Saturation?

Discussion in 'Mac mini' started by BigMcGuire, Jan 12, 2016.

  1. BigMcGuire macrumors demi-god

    BigMcGuire

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    #1
    Setup: Mac Mini Late 2014 with USB 3.0 enclosed Samsung Evo 850 (500GB) SSD running Mac OS X. I have an external USB 3.0 Sata to USB 3.0 adapter doing time machine backups to a 1TB WD Black (7200rpm). Razer gaming mouse + logitech gaming keyboard from PC gaming days (USB). The 2 thunderbolt ports are being used for dual monitors.

    Question: Do I need to worry about saturating the USB 3.0 bus? From what I can tell the USB 3.0 is limited to 5GBPS or 625mb/sec - and that's for all 4 USB 3.0 ports together, right?

    Any suggestions, comments welcome - thanks for your time,
     

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  2. treekram, Jan 12, 2016
    Last edited: Jan 12, 2016

    treekram macrumors 6502a

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    #2
    I have a couple of Evo 850 250GB SSD's internal in my 2012 MBP. Before I set it up as RAID 0, I was getting anywhere from under 300MB/s to under 500MB/s write and about 500MB/s read (Blackmagic). So it's faster than what you're experiencing, but from what I've read, it's not unexpected, given you're using USB. There's a review of the Samsung T1 USB SSD where they got 423MB/s read, 393MB/s write (Blackmagic). It could be that the USB interface T1 is better tuned to running an SSD over USB than whatever enclosure/docking station you use. But what you're seeing is not terribly out of the ball park, I think.

    (As a comparison, on my 2014 Mini I have the Monster Digital Thunderbolt 240GB SSD, which I understand uses the Crucial M500 internals. The M500 is an older SSD but I get (Blackmagic) 300MB/s write, about 500MB/s read.)

    From what I see in my 2014 Mini, all USB devices share one bus. The System Report no longer reports what bus is being used for each USB port, but the way the report is presented, compared to my 2012 Mini and from what I've seen on the web (mainly from audio enthusiasts who use a USB DAC), that is the case.

    Are you saturating the bus the USB is on? I don't think so because based on how long TM backups can take, it doesn't seem to me to be very disk intensive. If you were doing your first backup from the Evo to the external HDD, maybe there would be some contention. Obviously if you're backing up the Evo to the external HDD, the backup is using the Evo and that, more than bus contention, would have a performance impact that you may experience. In other words, if you were backing up to the internal HDD, I don't think you'd notice much difference in system response. The input devices are pretty much a non-factor. The Thunderbolt ports have their own buses.

    If you would like to avoid bus contention, avoid doing disk-intensive work while a backup is being done or manually do the backups when you're going to be away from the computer. (You can still do scheduled backups but by manually doing one while the computer isn't being used, you can reduce the amount of work the scheduled backups have to do.)
    You can also move the Evo to the internal SATA port of the Mini. It's a pain to install and maybe you want to keep the HDD there, but the SSD will be faster and there won't be any other device sharing the bus that the SATA interface uses. Finally, maybe you can research or somebody can suggest a USB enclosure that gets performance similar to what the T1 gets.
     
  3. Fishrrman macrumors G3

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    #3
    OP wrote:
    "Setup: Mac Mini Late 2014 with USB 3.0 enclosed Samsung Evo 850 (500GB) SSD running Mac OS X."

    Specific information needed:
    What you posted above isn't clear.
    Are you saying that you have a Samsung drive in some sort of USB3 enclosure?
    If so, what is the specific MAKE of the enclosure?
    When you bought it, was it advertised to specifically support UASP (USB attached SCSI protocol)?

    Important:
    You can't achieve full USB3 speeds unless the enclosure/dock/dongle that you're using supports UASP.

    I have a late 2012 Mini.
    For my 10.8.5 "external booter", I use an Intel 530 series SSD sitting in a plugable.com "lay-flat" docking station with UASP support.
    I get reads of 431mbps and writes of 271mbps.

    I also suggest that you temporarily disconnect the backup drive.
    Also it might be necessary to re-arrange your USB connections on the back of the Mini.
    Reason:
    I believe the 4 USB ports on the back of the Mini represent 2 different busses. If you use a slower speed device (such as a keyboard on the same bus as a fast device (such as the external SSD), the slower device may impact the overall speed of that particular bus.

    I opened System Information on my Mac and there are FOUR USB busses represented (see pic below).
    I believe one of these (on which Bluetooth resides) is internal and doesn't offer external connections.
    I believe another (shows up simply as "Hub" below) is for the SD card slot.
    Another bus represents one of the two available via the rear ports, and it indicates that my USB keyboard and USB (wireless) mouse are connected.
    The fourth bus (into which the SSD is connected) shows up as "SuperSpeed", and I believe this "boost" is because it has a drive connected which supports UASP.
    (Note: I could be wrong about the number of busses, perhaps others will step in and offer corrections)

    You might check your own Mini using System Profiler to see how your external devices are "lining up" on the busses.
    And, if necessary, re-arrange them so that the boot volume is "on its own bus" ...
     

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  4. BigMcGuire thread starter macrumors demi-god

    BigMcGuire

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    #4
    Very interesting - I believe my enclosure supports UASP - when I was setting it up I was told this was necessary to install OS X on an external drive. http://www.amazon.com/Anker®-Drive-...452701692&sr=8-1&keywords=anker+2.5+enclosure is the enclosure that I'm using for the SSD.

    I am using this: http://www.amazon.com/Anker®-Conver...452701914&sr=8-1&keywords=anker+usb+3+to+sata for the 1TB WD Black for Time Machine backups (and want to use it for the WD Velociraptors).

    When I get home from work I'll check out the System Profiler - thank you very much for the info. Waiting for a USB 3.0 extender for my mouse/keyboard so I can put them into 1 usb 3.0 port and my OS drive can be solo on 1 of the 2 USB busses in the back. (The Time Machine drive can share a port with the mouse and keyboard).
     
  5. treekram macrumors 6502a

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    #5
    Fishrrman, I can't view your image - it says it contains errors.

    What I see on my 2012 Mini is "USB 2.0 Bus" with my keyboard mouse, "USB 2.0 Bus" with Bluetooth and the IR Receiver and "USB 3.0 Bus". I don't see a fourth listing that ends with "Bus".

    On my 2014 Mini, which the OP has, there is only one listing at the left-most level which ends with the word "Bus". That's why I believe the 2014 Mini has one bus for all USB devices and the IR Receiver and Bluetooth.

    So I did an experiment with my 2014 Mini. I did the default Blackmagic test for a Seagate HDD 2TB bus-powered USB3 external drive. All USB devices were connected directly to the Mini

    Test 1: Seagate 2TB and USB keyboard/mouse. Did some movement of mouse
    Test 2: Seagate 2TB, USB keyboard/mouse, DVR box (USB2) recording a 1080i stream (2MB/s).
    Test 3: Seagate 2TB, USB keyboard/mouse, DVR box recording, USB2 external drive copying file to internal HDD.
    Test 4: Only Seagate 2TB, controlled computer via Screen Sharing.

    The results from the Blackmagic test were consistent in all 4 tests - 107-110MB/s read and write. Test 1 did have 103 MB/s write.

    What that tells me is that the number, speed or level (USB2 vs. USB3) of the devices on the USB bus (remember, the 2014 Mini only seems to have one bus for all USB devices) does not affect the throughput of another device on the bus, as long as they're not exceeding the total throughput of the bus. I don't have multiple, let alone one USB SSD to test but I would guess multiple USB SSD's will saturate the bus.

    BigMcGuire, I just took a very brief glance at the 3-star reviews for the Anker device. A couple that I saw:

    "Update: Anker contacted me directly and offered a refund after a few back and forth emails, so I moved the stars from 1 to 3 - they also explained the my Samsung 850 EVO 500GB SSD was not compatible and that other SSD's would work. While I'm thankful for the customer service, the enclosure isn't the best - I still recommend going elsewhere for your SSD enclosure needs until Anker releases an updated version." (9/7/2015)

    "Reached about 250MB/s on my 250GB Samsung 850 Evo, everything was well until it died less than a year later." (12/21/2015)

    The last comment shows at least one other person is getting the same speed you are (although that's a 250GB vs. your 500GB which may result in some difference).

    I found this article on the web: http://techreport.com/review/27690/samsung-portable-ssd-t1-reviewed

    One quote from this article:
    "We didn't have the courage to perform open-heart surgery on our drive, but Samsung tells us the T1 uses the same eight-channel controller and 32-layer V-NAND as the 850 EVO."

    I mentioned earlier that at least one reviewer was getting noticeably better throughput on the T1 than you are with the Evo using USB. So I still think if you look for a different enclosure you'll get better speeds.
     
  6. Gav2k macrumors G3

    Gav2k

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    Jul 24, 2009
    #6
    As above the layout on the back of the mini if you look at the ports are 1/2 are on the same bus and 3/4 are on another. Just keep the drives on separate busses and you'll get better saturation.
     
  7. treekram macrumors 6502a

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    #7
    Using Safari (vs. Firefox), I can see Fishrrman's graphic. It's different from what I see on my 2012 Mini, which shows 3 buses for USB devices. I have a i7 quad-core 2.6Ghz running 10.11.2. I'd be interested to know what you have. My 2014 Mini is the 2.6Ghz i5 and that shows only one bus for all USB devices. I'd be interested if somebody shows more than one bus for the USB devices. FWIW, on my 2009 Mini, there are 4 buses for the USB devices.
     
  8. BigMcGuire thread starter macrumors demi-god

    BigMcGuire

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    #8
  9. Gav2k macrumors G3

    Gav2k

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    #9
  10. Fishrrman macrumors G3

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    #10
    OP wrote above:
    "Very interesting - I believe my enclosure supports UASP - when I was setting it up I was told this was necessary to install OS X on an external drive. http://www.amazon.com/Anker®-Drive-...452701692&sr=8-1&keywords=anker+2.5+enclosure is the enclosure that I'm using for the SSD."

    I looked at the link you provided, and (my eyes, and me, are gettin' older) I don't see any indication that the item supports UASP at all.
    Rule to go by: If it doesn't SPECIFICALLY STATE that it has UASP support, it probably doesn't.

    In post #8, the OP wrote:
    "I just ordered http://www.amazon.com/gp/product/B00DW374W4?psc=1&redirect=true&ref_=od_aui_detailpages00 - will be getting it tomorrow so tomorrow after work I can tell you all the speed difference."

    Again, as I review the amazon page you posted, I see NO MENTION of UASP support.

    Here is an Inateck enclosure that DOES advertise UASP support:
    http://www.amazon.com/Optimized-Ina...=1452711680&sr=8-1&keywords=inateck+usb3+uasp

    Do you see the difference?
     
  11. BigMcGuire thread starter macrumors demi-god

    BigMcGuire

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    #11
    Wow .... I do... thank you very much for taking the time to write that. Cancelled that order and ordered the one you linked. I looked at the comments but didn't pay attention to the title as I should have. Will arrive tomorrow.

    Thanks again :)
     
  12. treekram macrumors 6502a

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    #12
    My System Reports (left is 2012 Mini i7 2.6Ghz, right is 2014 i5 2.6 Ghz):

    2012MiniSystemReport.png 2014MiniSystemReport.png
     
  13. BigMcGuire thread starter macrumors demi-god

    BigMcGuire

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    #13
    Interesting, so theoretically the max limit any one of those ports back there can handle (of the 4 USB 3.0 ports) is 625mb/sec (est) - and that's all shared.

    Wonder if using bluetooth keyboard/mouse uses less USB bus bandwidth than a USB gaming mouse (high DPI) and keyboard.
     
  14. treekram macrumors 6502a

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    #14
    One of the mice will require more bandwidth than the other (likely the gaming mouse), but you won't notice a difference because relative to storage devices or the overall speed of the USB bus, it generates little traffic.

    Other than having multiple USB SSD's, I don't see how one can saturate the single USB bus on the Mini. You could have an application that is very disk intensive and uses the SSD to the max while you want to copy a file from a USB HDD to the internal HDD, but if you don't know that you have that application, you likely don't have that application. Copying from the USB SSD to the USB HDD will be dictated by the speed of the HDD so that won't saturate the bus. It's the same with backing up from a USB SSD to a USB HDD. And as I mentioned before, if anybody has concerns about the throughput of the USB bus, put an SSD on the internal SATA port or try to get a compatible PCIE SSD.
     
  15. BigMcGuire thread starter macrumors demi-god

    BigMcGuire

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    #15
    Late 2014 Mac Mini (i5 with 8GB of ram) - looks like it's all on one bus.

    Will report tomorrow when I get the correct external enclosure (thank you @Fishrrman ). Screen Shot 2016-01-13 at 5.39.37 PM.png
     
  16. Partron22 macrumors 68000

    Partron22

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    #16
    This seems about right. I have about the same setup as the OP, and have noticed that USB II devices hooked to my USB III hub seem to, at least sometimes, pull down overall speed. I hook my wired keyboard and Evo 850 straight to the back of the mini. Mouse is bluetooth.
    Unless I've got a second mouse or something weird hooked up to my external hub I get nice fast thruput to multiple USB III drive caddies.
     
  17. BigMcGuire, Jan 14, 2016
    Last edited: Jan 14, 2016

    BigMcGuire thread starter macrumors demi-god

    BigMcGuire

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    #17
    Well... just got home. Put my EVO 850 into the Inatek case. First thing I noticed with the inateck case was that OS X booted up almost 2x as fast as before (which was already fast).

    Screen Shot 2016-01-14 at 3.12.15 PM.png

    That is an insane speed boost. UASP ftw.

    For comparison - Below: old results with the anker 2.5 enclosure. (Above was with the $15 inateck enclosure).

    Screen Shot 2016-01-12 at 6.40.42 PM.png

    Thank you all for your help. Much appreciated :)
     

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