Why is the iMacs 1TB SSD slower than 1TB SSD of a MBPr?

Discussion in 'MacBook Pro' started by breiti, Nov 4, 2013.

  1. breiti macrumors newbie

    Nov 1, 2013
    Hi folks,

    i actually searched for benchmarks and the late 2013 iMac's 1TB SSD options "just" get ~700MB/s.

    The 1TB SSDs in the MacBook Pro Retinas get ~1000MB/s.

    Iam about to purchase an 27" with an 1TB SSD but this is sad? So much money but worse performance than a notebook. :-(
  2. maz-o macrumors member


    Jul 16, 2010
    My guess is your iMac performance will still blow you away.
  3. dusk007 macrumors 68040


    Dec 5, 2009
    There is virtually no point to all this SSD speed. It doesn't matter. The CPU will in almost all cases lag behind. The only thing that is really noticably faster is unpacking non compressed archives or direct copy operations. In many cases copying files is limited by the source or target drive which is no where near as fast. Application performance is usually CPU limited and only really cares for random file access speed not so much bandwidth.

    1TB/s SSD max sequential performance past a certain point is really mostly for masturbating to benchmark numbers.
  4. auero macrumors 65816

    Sep 15, 2006
  5. Tobias Funke macrumors 6502a

    Tobias Funke

    Apr 3, 2012
    So do the iMacs. :D
  6. PDFierro macrumors 68040

    Sep 8, 2009
    You won't even notice a difference in real world usage. Don't worry about it.
  7. auero macrumors 65816

    Sep 15, 2006
    Well look at that! I stand corrected. :)
  8. m98custom1212, Nov 4, 2013
    Last edited: Nov 4, 2013

    m98custom1212 macrumors 6502

    Jul 20, 2013
    Toledo, Ohio

    No it doesn't. Where did you come with this?

    Every made a ram disk? Programs load instantly

  9. john123 macrumors 68020


    Jul 20, 2001
    This is simply untrue. It depends entirely on what you're doing and how you're doing it. As I just noted in another thread, disk I/O is the bottleneck for many database operations.
  10. breiti thread starter macrumors newbie

    Nov 1, 2013
  11. Freyqq macrumors 601

    Dec 13, 2004
    I would be very surprised if it wasn't the exact same SSD used in both computers. I bet they just used different benchmark software or some other reason for the difference.
  12. dusk007 macrumors 68040


    Dec 5, 2009
    Disk I/Ops has very little to do with max sequential read/write. Not that database operations matter much on a notebook but the Apple (or Samsung) SSDs used with those highe 700+MB/s read speeds don't really do any better in IOPS than much much slower drives. Actually there are quite a few drives that are much faster in the IOPS department because that is clearly not what Apple optimized for. For database operations these aren't ideal drives. If you want to setup a database cluster you'd probably use different ones with possible much slower sequential speed but higher iops. It is a firmware optimization thing.
    Disk I/O isn't just bandwidth and pure bandwidth is rarely the problem. Run any serious database benchmark and check what the actual MB/s read/written is and it will come in way way lower than the max seq read/write speeds which are the matter of this discussion.
  13. simon48 macrumors 65816


    Sep 1, 2010
    This is not true. If the CPU is lagging behind the CPU would show spikes to 100% when the SSD is maxed out and it doesn't. The SSD can transfer the data the the RAM which is way faster the any SSD.
  14. john123 macrumors 68020


    Jul 20, 2001
    I wasn't contending that sequential read/writes were the barometer of DB performance. But these drives are better than their previous generation in both sequential and random -rw.
  15. happyhacking macrumors member

    Dec 30, 2012
    So ?

    The we can conclude that MBPr 1TB SSD is faster than iMac 2013 1TB SSD ?
  16. PDFierro macrumors 68040

    Sep 8, 2009
    Looks that way, but what difference does it make?
  17. yjchua95 macrumors 604

    Apr 23, 2011
    GVA, KUL, MEL (current), ZQN
    The 1TB SSD in the rMBPs are 4-lane PCIe channels. All other capacities are 2-lane. That's why you can get read/writes of around 1.2GB/s on a 1TB SSD rMBP.1

    The SSD in the iMacs are all 2-lane PCIe, regardless of capacity.
  18. breiti thread starter macrumors newbie

    Nov 1, 2013
    Are there any IOPS benchmarks for the both SSDs available anywhere?
  19. SimonTheSoundMa macrumors 6502a

    Aug 6, 2006
    Birmingham, UK
    Are you sure the 1TB uses 4 lanes?

    CPU only supports 16. 8 for GPU, 2 for SSD, 4 for TB, 1 for USB3 and one for slow devices such as USB2 (keyboard, trackpad, isight, audio) networking and bluetooth.
  20. Quu macrumors 68030


    Apr 2, 2007
    I've had two rMBP 15" with 1TB SSD and neither went over 1GB/s - PCIe 2.0 is 500MB/s per lane, so two lanes would be 1GB/s.

    I've not seen any that went to 1.2GB/s as claimed in an earlier post in this thread so I would assume it is in-fact PCIe 2.0 with 2 Lanes.

    As for the iMacs lower performance? I have no idea.

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