Why is data transfer so slow on OWC 115gb SSD?

Discussion in 'MacBook Pro' started by pjny, Mar 27, 2011.

  1. pjny macrumors 6502a

    Feb 18, 2010

    I just installed a 115GB OWC Mercury Pro SSD as the boot drive on my 2010 Macbook Pro.

    I had Disk Activity on in the Activity Monitor while transferring files and exporting images etc.

    Copying images from one folder to another I got peak data reads of 65mb/sec and 60 mb/sec write.

    Writing to an external USB 2.0 7200 rpm drive got peaks speeds of about 37-40 mb/sec read&write.

    I understand the USB 2 and 7200rpm max would be about 70mb/second tops(read/write) but how come read-write speeds when copying files to the desktop on the SSD top out at 70mb/second instead of about the advertised 200-250mb/second read/write rates.
  2. aldejesus macrumors regular

    Feb 3, 2011
    Strange. I have a 120GB 1 week old and it read/write above 240+. I'm getting a new 115GB that should arrive on monday and will let you know.
  3. pjny thread starter macrumors 6502a

    Feb 18, 2010
    The SSD has the latest firmware 360A13F0 istalled.

    I installed the SSD in the DVD slot using the Data Doubler from OWC. The Macbook does operate faster (boot time is about 14 seconds before desktop appears) but it not significantly faster when processing RAW file images using Adobe Lightroom. There is still a delay in cycling through other images when Lightroom starts exporting images to JPG format.

    Is there a hard drive benchmarking tool I can download to make more tests?


  4. lithast macrumors newbie

    Mar 19, 2011
    You can find the tool that OWC uses to benchmark the drives here.

    You should be seeing read/write speeds between 260-280mb/second on average with this tool (mine does). If not then I'd suggest their live chat support, they were very helpful last time I had to speak with them.

    Best of luck.
  5. pjny thread starter macrumors 6502a

    Feb 18, 2010
    Tests using Aja System Test

    Thanks. I got 185.3megabytes/sec(write) and 226.5mb/s(read) using a 4gb block with Aja System Test program. Is this about average? Seems a lot lower than the advertised speeds.

    In comparison the Apple 5400rpm 500gb drive topped out at 64.5mb/s read/write.

    Is Aja System Test accurate for SSD?

  6. paulrbeers macrumors 68040

    Dec 17, 2009
    Looking at your numbers, everything seems pretty much in order.

    USB has a max of 480mb/s which works out to only about 60Mb/s but in real world experience you are never going to see anything about 40Mb/s.
  7. johnnyturbouk macrumors 68000


    Feb 9, 2011
    on the yellow [oled] brick road to tech nirvana.
    Are the advertised speeds not for compressable data?
    Where as OP is working mainly with compressable data, well in the 1st instance
  8. altecXP macrumors 65816

    Aug 3, 2009
    the 120GB SSD's have faster write speeds, and the 115GB SSD's have higher read speeds. It's due to the size of the NAND used.
  9. MacHamster68, Mar 28, 2011
    Last edited: Mar 28, 2011

    MacHamster68 macrumors 68040


    Sep 17, 2009
    read/ write speeds are always advertised as max possible and the operative word is POSSIBLE and has nothing to do with reality when actually WORKING , sure boot times improve an apps open faster , but that about it even a ssd cant create wonders with compressed files which need to be uncompressed and compressed again forwards and backwards
    thats why i settled for a velociraptor 600gb as i need space to work and i only use external drives as backup for finished jobs ,after reading various sources about pro and cons of ssd, and at the end the velociraptor hdd 10000rpm won for me , more speed compared to a 7200rpm drive and more capacity for less money compared to a ssd a

    and after i bought it there came tom's hardware (ok they compared ssd's and the velo on windows 7 ) but they came to near the same conclusion velo if you need space to workbut more speed then conventional Hdd's and intel G2 if you need more speed and dont need space
    jut read the article http://www.tomshardware.com/reviews/windows-ssd-performance,2518.html
    and yes i know the velociraptor is a 3.5" desktop drive ,if !you leave the ice pack attached but in reality its a 2.5" if you take a screwdriver and get rid of the ice pack ( a version without icepack is available but only 150/300GB)
  10. brentsg macrumors 68040

    Oct 15, 2008
    Also note that review samples are often SSDs of larger capacity, which have a significant performance advantage.
  11. Consultant macrumors G5


    Jun 27, 2007
    Yup. Exactly.
  12. MacHamster68 macrumors 68040


    Sep 17, 2009
    its just a advertisement practice , they want to sell and a good selling point is topspeed ,
    the Bugatti Veyron supersport is advertised with 431.07 km/h (267.85 mph) , nowhere in the add is talk about that you stuck like everybody else in the rush hour hardly ever reaching 50km/h (31mp/h)through town when actually using it as a normal car for getting to and from work
  13. pjny thread starter macrumors 6502a

    Feb 18, 2010
    macperformance guide results on 115gb ssd

    MPG review of the 115gb OWC SSD explains why I was not getting the magic boost from SSD for image processing programs like Adobe Lightroom:

    "All of my photographic work involves digital camera RAW files. About 95% of my data is image files, which are mostly incompressible. Incompressible data is a worst case for the Mercury Extreme Pro 115GB.

    Something about pure random data with the new 25nm flash memory makes the Sandforce controller sluggish for writes. While the read/write performance is consistent across the capacity (not an erratic loss of general performance), the write speeds are slower than a laptop hard drive, or even Firewire 800.

    As shown below, the OWC 115GB SSD can write compressible data at about 253 MB/sec, and read it at about 270.7MB/sec — this is nearly as fast as a SATA 3Gbps controller can deliver in the real world.

    When forced to write incompressible data (worst case), speed drops to 75.9 MB/sec and read speed to 235.2 MB/sec. That’s a minor impact for reads, but a 70% drop in write speed."

    Do other SSDs have this WRITE problem with incompressible data? I paid a premium for a speed boost and I am not seeing it from the OWC drive when it comes to processing images/incompressible data.
  14. bamf macrumors 6502

    Feb 14, 2008
    I believe that is mainly an issue with Sandforce based controllers - which the OWC drive in question uses.
  15. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Read over page five and six of this review. In his comments Anand seems to imply Sandforce (in the Vertex drive) is using some sort of trickery with compression to allow better performance under normal circumstances, but this falls down when using uncompressable data. I know the review is a Vertex 3, but the Vertex 3 uses an updated version of the Sandforce controller in your OWC. Could be the same issue?
  16. pjny thread starter macrumors 6502a

    Feb 18, 2010
    MPG states that the switch to 25nm may have affected write performance because the 200gb OWC drive does not have the same issue. Might have to return the drive because I paid $265 for SSD+Disk Doubler. Not happy. Sta away from this drive.

    MPG states:

    "As confirmed with the DiskTester sustained transfer results below, the OWC Mercury Extreme Pro 115GB SSD shows impaired performance over its 34nmm 200GB sibling. Whether this is an issue with all SSDs using 25nm flash memory or specific to the 115GB model won’t be clear until other capacities are tested. It’s also likely that the Sandforce generation 2 controller will improve upon this, but that remains to be seen.

    The difference is about 13% between the Apple SSD and the OWC 200GB Mercury Extreme Pro RE SSD. This is a worst case for the OWC SSD (mostly incompressible data)."


  17. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Very interesting. So it does look like the OWC switch to 25nm NAND affected performance. I see the MPG article mentions the issue with noncompressable data and Sandforce controllers also.

    You may want to get something other than a Sandforce SSD?

    I find this all very interesting after the thrashing OCZ took for switching to 25nm NAND and there is hardly a peep from anybody about OWC doing exactly the same thing and not telling purchasers. If you go to their site to buy a drive now as opposed to a couple months ago there is absolutely no mention of the fact the same "Mercury Extreme Pro" switched from 34 to 25nm NAND. Very shady move IMO.

Share This Page