How many SATA III HDDs could a Mac Pro make use of?

Discussion in 'Mac Pro' started by Ravich, Sep 12, 2010.

  1. Ravich macrumors 6502a

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    #1
    Using a SATA III controller through PCI or whatever.
     
  2. Hellhammer Moderator

    Hellhammer

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    #2
    Couldn't find a controller with more than 4 ports (link) so you could have at least 12 HDs unless there are some other restrictions. Of course you can use SATA splitter/hub or enclosures to get even more HDs
     
  3. Ravich thread starter macrumors 6502a

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    #3
    Arent there bandwidth limitations as well or something? Like when the next generation of SSDs comes around, SATA II is going to be bottlenecking them, so... I'm wondering how many, say, 500MB/sec read SSDs running at full blast could be supported.
     
  4. Hellhammer Moderator

    Hellhammer

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    #4
    Well, Mac Pro has two x16 slots (I think) and two x4 slots and each lane has bandwidth of 500MB/s so x4 has total bandwidth of 2GB/s. That means 500MB/s per SSD if you have all four in use so there should be any bottlenecks. So far, the fastest 6Gb/s SSDs seem to be Crucials and they can only provide 355MB/s. This will change though.
     
  5. Ravich thread starter macrumors 6502a

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    #5
    Huh... well that's pretty comforting. Not ideal, sure, but still workable. A while back I heard someone talk about limitations of the PCI slots as though you had to use one of the x16 for a single SATA III HDD.


    One of the x4 slots could also support lightpeak then, right?
     
  6. Hellhammer Moderator

    Hellhammer

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    #6
    The numbers I gave are theoretical maximums, I don't know what are they in real world.

    LightPeak has bandwidth of 10Gb/s (that is what has been demonstrated, up to 100Gb/s according to Intel) and that is equal to 1.25GB/s so yes, PCIe x4 which can provide 2GB/s should be able to run LightPeak fine. It would run it even though it couldn't run it at full speed. Remember that that 1.25GB/s is the bandwidth of one LightPeak port so if you had two of them, that would be 2.5GB/s which is faster than what PCIe x4 can provide. It will take time before we see mainstream SSDs that can deliver sequential speeds of over 1GB/s though.
     

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