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Thread: I/O data rates using Thunderbolt 1 devices on different ports vs. being daisy chained

  1. #1
    Join Date
    Sep 2007
    Location
    Edmonds, WA
    Posts
    19

    Default I/O data rates using Thunderbolt 1 devices on different ports vs. being daisy chained

    I have three LaCie 2big Thunderbolt-1 devices that are to be connected to a new MacPro 6,1 next week. In addition I will be connecting a 5-bay Burly Port Multiplier eSATA enclosure as well.

    1) 4TB RAID-0 LaCie 2big
    2) 4TB RAID-0 LaCie 2big
    3) 6TB RAID-0 LaCie 2big
    4) 20TB Burly Port Multiplier eSATA enclosure

    The MP6,1 has 3 separate Thunderbolt-2 busses as shown below



    Ignoring the Burly device for time being I could connect the three LaCie devices to separate Thunderbolt Buses 0, 1 and 2 to configure separate data paths for each of them. If I do this I would have to connect the Burly to one of the Thunderbolt Buses being used by one of the LaCie devices.

    The Burly will be connected to the MP6,1 using a 3m Thunderbolt cable --> Sonnet Echo Express34 Adapter + eSATA Pro Expresscard 34 --> eSATA cable --> Burly. This provides full access to all 5 disks as RAID and/or JBOD, plus allows for hot-swapping.

    My question is related to daisy chaining the LaCie devices and what this may mean to expected data rates compared to them not being daisy chained.

    So let's say I use Thunderbolt Bus 1 to connect all three LaCie devices setup in a daisy chain...

    Thunderbolt Bus-1/Port-1 --> 6TB RAID-0 LaCie 2big --> 4TB RAID-0 LaCie 2big --> 4TB RAID-0 LaCie 2big

    ...and connect the Burly on another Thunderbolt Bus, such as below

    Thunderbolt Bus-2/Port-4 --> Sonnet Echo Express34 Adapter + eSATA Pro Expresscard 34 --> eSATA cable --> Burly

    This configuration leaves Thunderbolt Bus-0 completely open for Display(s)

    If i/o is being done to the LaCie devices at same time will the data rates be less than if they were each on separate Thunderbolt buses ?

    Each LaCie RAID-0 device is capable of transferring data at around 300 MBytes/sec for large file i/o. So if all three LaCie devices were moving large files at same time we have some 1 GBytes/sec to deal with. Thunderbolt-1 is rated at 10Gbps or some 1.342 GBytes/sec. From this I would assume the aggregate data rates achieved using all three LaCie devices at same time be they daisy chained or not would be the same. What are your thoughts ?

    I do not expect all three LaCie devices to be used frequently at the same time.... but want to ensure that if they are their daisy chained configuration does not impact their i/o rates in any significant way.

    Of course, I could also daisy chain the Burly off the last LaCie device as well or use the same Thunderbolt bus the LaCie daisy chain string is using and only have to use one Thunderbolt Bus for all four devices. Let's say I did this using Thunderbolt Bus-1 with the LaCie daisy chain connected to Port-1 and the Burly connected to Port-3. This would allow Ports 2, 4, 5, 6 and HDMI open for other things.

    Thanks for your time....

  2. #2
    Join Date
    Jan 2002
    Location
    NW Montana
    Posts
    8,197

    Default Welcome to the Guru's forums

    Hang in here. I'll let someone with more multi drive experience get you started.

    I'm happy with a simple 1 or 2 fast drives no RAID and a good backup system.

  3. #3
    Join Date
    Aug 2001
    Location
    Grangeville, ID USA
    Posts
    9,148

    Default

    From February. Sorry I missed it.

    Short answer is it won’t matter. One bay drives are very low throughput.


    Rick
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

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