SSD Speed Comparison

Discussion in 'Mac Pro' started by choreo, Jul 6, 2015.

  1. choreo macrumors regular

    choreo

    Joined:
    Jan 10, 2008
    Location:
    Midland, TX
    #1
    I have two Macs, both with Samsung SSD Boot Drives:

    MacPro 2012 3.33 GHz 6-Core Intel Xeon w/32 GB 133 HMHz DDR3 Ram
    Velocity x2 PCI Card w/ two Samsung 500GB 840 EVO SSDs (one is boot drive with Mavericks 10.9.5)

    MacbookPro 17" 2011 w/ Samsung 500GB 850 EVO

    I just installed "Disk Sensei" on both machines to replace Trim Enabler and ran a couple benchmarks within that app on both machines. Can anyone tell me why the Powerbook appears to be so much faster than the MacPro? Launching Photoshop CC2015 on the older Powerbook takes 3 seconds. On the MacPro it takes about 10 seconds (for comparison). Is it because maybe the MacPro is SATA II and the Powerbook may be SATA III?

    https://www.dropbox.com/s/n2322h6egtmva13/MacPro_Disk_Sensei.jpg?dl=0
    https://www.dropbox.com/s/5kazc4h80xhtmsb/Powerbook_Disk_Sensei.jpg?dl=0
     
  2. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
    #2
    You hit the nail on the head. Your Mac Pro is sata 2 and the mbp is sata 3
     
  3. choreo thread starter macrumors regular

    choreo

    Joined:
    Jan 10, 2008
    Location:
    Midland, TX
    #3
    Thanks, that was all I could think of. There is such a big difference in the "latencies", that may be why apps are launching slower?
     
  4. SoyCapitanSoyCapitan macrumors 68040

    SoyCapitanSoyCapitan

    Joined:
    Jul 4, 2015
    #4
  5. choreo thread starter macrumors regular

    choreo

    Joined:
    Jan 10, 2008
    Location:
    Midland, TX
    #5
  6. SoyCapitanSoyCapitan macrumors 68040

    SoyCapitanSoyCapitan

    Joined:
    Jul 4, 2015
    #6
    The application caches in library/caches and system/library/caches

    Then you can check is the speed difference is the fault of RAM or something else
     
  7. choreo thread starter macrumors regular

    choreo

    Joined:
    Jan 10, 2008
    Location:
    Midland, TX
    #7
    No significant change.
     
  8. SoyCapitanSoyCapitan macrumors 68040

    SoyCapitanSoyCapitan

    Joined:
    Jul 4, 2015
    #8
    You will just have to chalk it up to the operating system not performing identically on both platforms. It's not SATA or the SSDs unless the 840 has degraded.
     
  9. Inutopia macrumors 6502

    Inutopia

    Joined:
    Apr 8, 2009
    Location:
    South of Heaven
    #9
    I think there's something wrong on the Mac Pro end. I just checked on mine and launching PS takes about 3 seconds.

    Do you have heaps of plugins installed on the Mac Pro that aren't on the laptop? What about fonts? Check your font book, errors there can slow down PS with large font libraries.
     
  10. Thessman macrumors regular

    Joined:
    Dec 8, 2005
    Location:
    GR
    #10
    The Velocity card is an adapter from PCI to SATA III, which depending on the exact model gives you about 800 MB/s max for both disks, not as much as 2xSATA III but much better than SATAII, so the reason for the delay should be something else. Do you have other PCI cards? which slot do you have your Velocity in?
     
  11. h9826790 macrumors 604

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #11
    Is your 840 Evo using the latest firmware? There is a bug in the old firmware. Slow reading on old data (e.g. 3 months old).

    The bug can reduce the 500MB/s reading speed to something like 25MB/s.

    You may try to copy some old file (e.g. the photoshop app) from the 840 Evo to another disk (use a RAM disk as target disk can eliminate the target disk speed limit). And check if you are suffering from this bug.
     
  12. subsonix macrumors 68040

    Joined:
    Feb 2, 2008
    #12
    You are talking about two striped disks right? The theoretical max for SATA III is 600 MB/s after taking encoding into consideration.
     
  13. Thessman macrumors regular

    Joined:
    Dec 8, 2005
    Location:
    GR
    #13
    No i'm talking 800 MB's total bandwidth, or 550 MB/s for one at a time, as is stated on the specs for the card, the solo x2 for example gives you two SATA III connectors, but the total usable bandwidth is up to 800 MB/s.
     
  14. subsonix macrumors 68040

    Joined:
    Feb 2, 2008
    #14
    Right, but 800 MB/s implies that more than one SATA port is used, since you can not get more data out of the port than the spec of the SATA III protocol, no matter what the card says. SATA III provides 6 Gbit/s, i.e 750 MB/s, then the data is 8b/10b encoded, so each 10 bits carries 8 bits of data, so the theoretical max of SATA III is 750 * 0.8 = 600 MB/s.
     
  15. Thessman macrumors regular

    Joined:
    Dec 8, 2005
    Location:
    GR
    #15
    You're correct of course, I just stated that it's a SATA III adapter (with a bandwidth equal to a real SATA III, give or take a few MB/s, as the actual sustained data rate of a SATA III ssd never exceeds 565 MB/s.) because Gav2k suggested that the SATA II interface of the Mac Pro is the culprit for the reduced performance of choreo's ssd.
     
  16. kennyman, Jul 8, 2015
    Last edited: Jul 8, 2015

    kennyman macrumors regular

    Joined:
    May 4, 2011

Share This Page