Hard drive options, Raid over FW800, Raid enclosure in iMac, etc Technical questions.

Discussion in 'Buying Tips and Advice' started by dannys1, Jan 31, 2010.

  1. dannys1 macrumors 68000

    dannys1

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    #1
    Hi guys,

    Im in the process of buying a 27" i7 iMac. I never use the optical drives so im going to take it out and my idea is to install two Intel X25-M G2 160gb drives in a software raid 0. This is my decision so thats not the question.

    However in another thread someone had shown a 3.5" adapter which took two 2.5" drives and create a hardware Raid 0 array. I presume the iMac has a 3.5" drive in it then? If you were to create a Raid 0 SSD array in an enclosure like this would the 3gb Sata connector be too slow to take advantage of it, would it be faster to have the two SSDS on separate sata busses and connected via software raid?

    IF its just as fast to put them on one sata connecter id be tempted to do that and throw in a 1tb drive in the optical slot and this would solve a lot of problems for me.

    As the next issue is, I need another 2tb of space for my huge sample libraries on the computer. Obviously im limited to FW800. ive got a number of redundant sata drives and ive been looking at the external dual disk raid enclosures. My question is would you see the benefit of two 7200rpm drives in an external raid 0 enclosure when connected over FW800 or would the FW800 connection bottom out with a single drive anyway??

    I look forward to peoples input. :apple:
     
  2. Transporteur macrumors 68030

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    #2
    You are facing two serious bottlenecks here.

    Even though SATA II has a theoretical bandwidth of 375MB/s, the real life maximum throughput levels off at about 270MB/s.
    A single Intel G2 operates pretty close to that value. They make a sequential read of 250MB/s+, hence a second Intel on the same SATA bus would not make any sense as you won't get any more performance.

    FW800 has a real life bandwidth of approximately 80MB/s, a single 7200RPM 2GB drive, such like the Western Digital Black, has an average read/write performance of ~110MB/s. So yes, FW800 drastically limits the speed of a RAID0 out of two 7200RPM drives.
    For best hard drive performance, the iMac is definitely the wrong machine.
     
  3. Hellhammer Moderator

    Hellhammer

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    #3
    SATA2's maximum transfer rate is 375Mbytes/s (3Gbits) and dual Intel X25-M G2s have maximum read speed of ~500Mbytes/s (~250Mbytes each, can't remember the exact number) so you would lose speed (~125Mbytes/s) plus if you're writing something at the same time you would lose even more. So it would be better to have them in separate SATAs and then connect them with software RAID.

    FW800 is limited to 100Mbytes/s, so you might bet a small boost from RAID0 but it won't be huge, probably 10-20Mbytes/s. I can't recommend any model or brand but RAID enclosures usually costs more than normal ones so be ready to pay some extra
     
  4. dannys1 thread starter macrumors 68000

    dannys1

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    #4
    Ah ok...seems a bit pointless that they make Raid 0 enclosures at all then doesn't it?

    So in otherwords it would make more sense to save money and just buy a 2tb FW800 external drive as it'll perform near enough the same as two x 1tb drives in an a raid 0 enclosure and be much cheaper...

    The high performance is too much of a problem for me as I'll fit as much of the usable library as I can on the SSD, I just wanted the external to work as much as it can - but if a raid 0 over FW800 is pointless i'll just stick to a normal drive, its very unlikely my usage will call for faster speeds than this. Im going to put 16gb ram in my iMac anyway and this will load probably all my samples in one track into ram so I wont even need to stream to disk.

    As another option - has anyone swapped the mini-pci-e wireless card in the imac for anything else? There are numerous options out there, mini-pci-e to esata (which i learnt wont work because you can't just make a PCI into a Sata interface apparently...but there also mini PCI-E to Firewire 400 connecters (which would be very useful for me for various FW400 devices not sharing the FW800 bus. They even have a mini-pci-e to full PCI-E adapter which would be very very useful for me if it would as I could fit a UAD-2 card, which doesn't make anywhere near the useful of the full bandwidth of PCI-E (it only uses half the slot for instance)

    But im not sure if any of this is even possible on the iMac and in OSX.
     
  5. Transporteur macrumors 68030

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    #5
    Your transfer rates are the theoretical maximum values. Real-life performance is considerably slower, please see the numbers I stated above.
     
  6. Hellhammer Moderator

    Hellhammer

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    #6
    True.

    @OP: Why don't you get a Mac Pro? With iMac you are limited to one FW800 and replacing HD(s) isn't very easy or fast. Mac Pro will be updated within few months and it'll be worth waiting.
     
  7. dannys1 thread starter macrumors 68000

    dannys1

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    #7
    Few reasons..

    1. Dont have the time to wait.

    2. Fell in love with the new iMac and the screen...

    3. Cant get that screen anywhere else, the 24" isn't big enough and the 30" isn't as nice - for me the screen alone with inspire me to work.

    4. Dont have the extra budget to spec out the Mac Pro the way id want to, its more expensive to do and I dont want to spend an extra £500 - £1000 on a screen.

    5. Ive had the G5 for years and the only extra I had in it was the single UAD card and my soundcard - im upgrading to a better FW soundcard its just a shame it'll have to share the bus with the hard drive.

    It is limited but I think that limitation will just make me work instead. Although it is a shame the i7 iMac doesn't come with expresscard, an extra FW800 and an esata slot...that then would make it the most perfect machine ever made for me...
     
  8. Transporteur macrumors 68030

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    #8
    RAID0 via FW800 is pointless if you're simply considering performance, but they might become pretty useful in case that you want a large single array.
    2 x 2TB drives striped together would make a joined 4TB drive, which can't be done with a single drive, yet.

    IIRC someone tried this with a mini PCIe SSD in the airport slot of a Mac Pro. Worked out that the slot is solely supposed to work with Airport cards.
    Firmware and OS X don't support other hardware in these slots.
     
  9. dannys1 thread starter macrumors 68000

    dannys1

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    #9
    Ah...

    Well that would appear im being forced into getting rid of my dream idea of two SSDs as well as im reading the Apogee Duet has lots of problems if you daisy chain another FW device with it...not good.

    Especially as for some bizarre reasons all the basic DSP units seem to be Firewire 400 and not USB2.

    Could possibly be forced to go the Mac Pro route although I really dont want to as it'll destroy the budget...

    Hmmmm
     
  10. Transporteur macrumors 68030

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    #10
    Daisy chaining FW devices is definitely not a problem. I know quite a lot of people that use multiple daisy chained FW drives without any issues.
    I've got two Iomega Ultramax devices daisy chained on my Pro. Works flawless.

    But do you really need to stripe two Intel SSDs? Even a single one is so darn fast, there is not really a need to stripe them. I'm absolutely satisfied with the performance of the 160GB Intel G2 and haven't considered adding a second one yet.

    Instead of occupying both internal SATA ports with two SSDs, I suggest you go for a single Intel plus a 2TB mechanical drive in the ODD bay. Get an external DVD drive (USB or FW) and add backup or additional storage drives via FW800.
     
  11. dannys1 thread starter macrumors 68000

    dannys1

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    #11
    Unfortunately the Apogee Duet does not like being daisy chained ive just found out - which means I have to keep the FW800 bus clear just for it to work properly, which is a shame, I think its also because its just bus powered.

    My other option here is USB 2 for the hard drive, which in all honesty with be fast enough for a sample library.

    Your right I dont *need* dual SSD in raid, but while one is fast, two is twice as fast and ive spent years being bottlenecked by hard drives, id rather have the 320gb of space as I dont want to just have the apps on the SSD as ill see much bigger gains when im loading gigabyte sample patches and disk streaming rather than just booting or loading the program.

    there are options though with the drives, as you said put a 2tb 2.5" in the optical bay, SSD in the main, USB externally for backup etc - although in all fairness if I had the 2tb inside I wouldn't really need anything connected outside anyway so that would become a moot point.

    What is a problem though is there are two DSP processing devices I want to get which both run off Firewire 400 - which im not being told I cant daisy chain...

    So...is there a USB 2.0 hub at all which gives you a couple of Firewire 400 ports. I dont believe these devices will be anymore demanding on USB 2.0 than they will on FW400, if its possible and if they'll be seen at all...that is now the new problem.
     
  12. Transporteur macrumors 68030

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    #12
    2TB drives are only available in the 3.5" form factor. If such a drive does not fit physically in the ODD bay, you can put the SSD there. Doesn't make a difference performance wise.

    USB and FW are not compatible at all, hence there is no USB - FW adapter or hub.
    But instead of daisy chaining your devices, you can buy a simple FW800 hub and connect them to it, either directly via FW800 cables for hard drives, or FW800-400 cables/adapters for your (audio?) devices.
     
  13. dannys1 thread starter macrumors 68000

    dannys1

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    #13
    But thats only going to give me the same results as daisy chaining. Its still running from the same single Firewire Bus.

    Apogee state that duet needs to run on its own bus to be problem free.

    How does this connect to your mac? It doesn't state anywhere?
    http://www.belkin.com/aeona/?cid=6&pid=203160
     
  14. DoFoT9 macrumors P6

    DoFoT9

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    #14
    looks like fw400 (firewire 6 pin).
     

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