Looking for advice (nMP)

Discussion in 'Mac Pro' started by Bosh, Mar 6, 2014.

  1. Bosh macrumors newbie

    Sep 7, 2006
    I'm a little nervous about buying a nMP so before I do I wanted to confirm a few things.

    1. Internal hard drives - I currently have 4 internal drives and I'll move 3 of them into a Pegasus2 R4 (diskless). When I first heard about the nMP I assumed data would move slower to and from an external enclosure, but all the benchmarks show SATA being the limiting factor. My current drives get about 100MB/s read and write and from what I have seen I can expect at least double that from the R4. Does it matter that the drives are WD green drives ? I don't plan to set anything up in raid just yet, JBOD for now.

    2. Displays - I currently have a ATI Radeon 5870 with three monitors (30" ACD, 24" ACD, 23" Planar). The ACDs are using an Apple Mini DisplayPort to Dual-Link DVI Adapters, the Planer is connected directly to the DVI port. Do I need to buy an active adapter (resolution is 1920x1200) for the Planar monitor ? If I wanted to use a 4th monitor with a DVI cable, would it work with another active adapter ?

    3. Thunderbolt - With 3 monitors, a Pegasus R4, and possibly a LaCie 8TB 2big for backups; does it matter what items get plugged into what TB ports in the back ?

    Thank you in advance.
  2. ogilloire macrumors member

    Feb 22, 2014
    I think all these are answered in recent threads in the forum if you do your own little research you'll find a lot of interesting resources.

    1. No

    2. No

    3. Yes prefer to connect to separate TB buses for optimal perf, diagram available at Apple KB and AnandTech Mac pro review for instance
  3. JQuick, Mar 6, 2014
    Last edited: Mar 6, 2014

    JQuick macrumors member

    Feb 2, 2014
    This link describes multiple display support in the 2013 Mac Pro.

    Here are a few short answers to your specific questions.

    The ACDs with their current DL DVI adapters will work fine.

    The Planar with a passive adapter 1920s1200 should work.

    If you add a 4th display via DVI, your choice of active or passive will depend on the resolution and whether you want keep your HDMI port available. At 1920x1200 or lower, passive will work. For higher resolutions you will need an active adapter. Using a second passive adapter will also preclude connecting an HDMI display unless you remove one of the passive DVI displays.

    Only 2 HDMI and passive DVI displays may be used.

    Up to 6 Active DVI adapters may be used.
  4. VirtualRain macrumors 603


    Aug 1, 2008
    Vancouver, BC
    I'm not sure why you think your drive speeds will improve. If they run at 100MB/s today, they will run at 100MB/s in the Pegasus. The only way you can get added performance from them is to stripe them into a RAID0 array.
  5. Bosh thread starter macrumors newbie

    Sep 7, 2006
    My understanding is the SATA has a limit of about 100MB/s. No matter how fast the drive is, the amount of data that can delivered over a SATA bus is around 100MB/s.

    Thunderbolt's limit is MUCH higher.

    Thanks everyone for the responses so far.
  6. VirtualRain macrumors 603


    Aug 1, 2008
    Vancouver, BC
    SATA2 actually has a limit of 285MB/s. SATA3 double that. And while you're correct that Thunderbolt is much higher (~800MB/s for TB1 and double that for TB2), hard drives are limited by the speed of the drive, which as you point out in the case of WD Green drives is 100MB/s. The interfaces are not the limiting factor... it's the HD itself.

    The best analogy I've read goes something like this... Imagine your HD is a golf cart. Just because you put it on a 4 lane highway doesn't mean it can go any faster. If you want something that can tear it up on that Thunderbolt highway, you either need several drives in RAID0 or an SSD or two (also in RAID0).

    The bottom line is that you won't see any performance increase if you just move your HDs to the Pegasus. If you reformat them all and build a RAID0 array out of them, then you will get n x 100MB/s where n is the number of drives you stripe together.

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