Firewire 800 real transfer speeds

Discussion in 'Mac Basics and Help' started by brasiliangringo, Apr 22, 2009.

  1. macrumors regular

    Joined:
    Feb 18, 2009
    #1
    I have 1TB Seagate Freeagent external (15mb buffer / 7200rpm) connected to MBP. Transfering .avi files using firewire 800 takes about 20 seconds per gb so around 50mb a second - Is that not increddibly slow considering firewire 800 is rated upto 800 mb/s ?!!?:confused:
     
  2. macrumors 603

    richard.mac

    Joined:
    Feb 2, 2007
    Location:
    51.50024, -0.12662
    #2
    Firewire 800 is 800 Mbits/s (Mb/s) not 800 Mbytes/s (MB/s) [8 bits in a byte] its a common misconception. so Firewire 800 is rated up to 80 MB/s.

    in the real world no one gets 80 MB/s its usually just under 90% of the theoretical speed. also 50 MB/s is the average speed transfer, there are speed spikes that get up to ~70 MB/s.
     
  3. thread starter macrumors regular

    Joined:
    Feb 18, 2009
    #3
    jesus , what confusion - thanks for that..:eek:
     
  4. macrumors newbie

    soonlar

    Joined:
    Sep 1, 2007
    Location:
    Twin Cities, MN
    #4
    Correct bits to bytes calculation

    Firewire 800 is equal to approximately 800 Mb/s (megabits per second), since there are 8 bits in a byte, then this would be 100 MB/s (megabytes per second).

    You can check your math here:
    http://www.matisse.net/bitcalc/?input_amount=800&input_units=megabits&notation=legacy

    Technically speaking Firewire 800 actually allows a transfer rate of 786.432 Mbit/s full-duplex.
    http://en.wikipedia.org/wiki/IEEE_1394_interface
     
  5. macrumors 603

    gr8tfly

    Joined:
    Oct 29, 2006
    Location:
    ~119W 34N
    #5
    I get about 68MB/s going from internal 7200rpm to the same external you have.
     
  6. macrumors newbie

    soonlar

    Joined:
    Sep 1, 2007
    Location:
    Twin Cities, MN
    #6
    iMac 1TB to DroboFW with Firewire 800

    I am doing a copy right now, iMac to DroboFW using ChronoSync 4.1.0. I am only getting a peak of 21.5 MB/sec independently for reads and writes, but overall looks less than 45 MB/sec most of the time. Not as good as one would hope IMHO...
     
  7. macrumors newbie

    Joined:
    Nov 11, 2010
    #7
    I too get much slower speeds using Chrono sync. And that is with verify off. It is even slower on the first copy/backup/sync if you have verify on. That being said, once the data is on there, the syncs for changes are incredibly fast! I'm using firewire 800 and getting 28 or so megs a second on average copying photos (dng (12-20megs)and some smaller jpeg files) I suspect that copying large video files the speed will go up a little bit. When I remove the drives and copy via esata, I get around 50 megs a sec.) go figure!

     

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