USB2 DVD writer - crazy high cpu usage...

Discussion in 'Mac Accessories' started by brap, Apr 19, 2005.

  1. brap macrumors 68000

    Joined:
    May 10, 2004
    Location:
    Nottingham
    #1
    As far as I can tell this hasn't been covered already, but if it has, I can't find it!

    My external DVD writer, a Pioneer 107 on the USB2 bus, has issues. When writing, and when verifying, CPU usage hits 90%+, rendering everything else painfully slow; it's confusing since it seems determined to suck up every last bit of time - regardless of how else processing is distributed, the burn process grabs the remainder. This isn't solely limited to Toast (6.0.9), I find the same problems with Disk Utility.

    Is this a common 'feature' when using the USB2 bus for high-volume, sustained transfers? As far as I remember it was fine with an IDE hard disc. For reference, this is on a revision c. 12" Powerbook.
     
  2. MisterMe macrumors G4

    MisterMe

    Joined:
    Jul 17, 2002
    Location:
    USA
    #2
    This is hardly surprising. USB passes everything through the CPU.
     
  3. Jigglelicious macrumors 6502

    Jigglelicious

    Joined:
    Apr 25, 2004
    Location:
    NYC
    #3
    USB and USB 2.0 are highly CPU intensive. Try Firewire instead if you want to go the external route.
     
  4. brap thread starter macrumors 68000

    Joined:
    May 10, 2004
    Location:
    Nottingham
    #4
    Too expensive, late, yada yada. That, and I already have a Lacie D2 Extreme on my single, lonely FW400 port. I'm not spending any more money on a FW hub and enclosure, that'd be silly.

    A little update, the CPU usage issue seemed to be markedly less when using Disk utility... in contrast to the last time i tried. How confusing.

    I'll probably have to dump Toast if I can find a suitable alternative :eek: :eek:
     
  5. CanadaRAM macrumors G5

    CanadaRAM

    Joined:
    Oct 11, 2004
    Location:
    On the Left Coast - Victoria BC Canada
    #5
    Umm... Firewire is daisy-chainable, hub not necessary.
    In certain circumstances such as digital audio interfaces, it is best to have your FW drive and FW audio interface on different busses (not just different ports or a hub) but that is a specialized case.
     
  6. brap thread starter macrumors 68000

    Joined:
    May 10, 2004
    Location:
    Nottingham
    #6
    True - but say I'm burning something from my D2, bandwidth would be halved... perhaps closer to quartered?

    Eitherway, handling I/O for both devices along a chain (or hub) can't be too efficient. Bear in mind that the drive is being limited by the full bandwidth of FW400 as it is, without the extra DVD drive attached. So your audio example is, actually, quite relevant.

    ...not to mention the fact the D2 only has one 400 port. Yeah, I could get a converter, but again... I've spent far too much on gadgets this month as it is!! I'd much rather have a functional D2->FW400->Powerbook->USB2->107D connection, thus using the theoretical bandwidth sensibly. Hopefully possible as soon as Toast either gets an update, or I find some freeware to do the job :eek:

    Anyway, back on track; so nobody has ever come across Toast 6 throwing a paddy when using USB2?
     
  7. CanadaRAM macrumors G5

    CanadaRAM

    Joined:
    Oct 11, 2004
    Location:
    On the Left Coast - Victoria BC Canada
    #7
    Sorry, I don't see it. Drive access / CD access when burning a CD is sequential (read, then write). Drive access/interface access when capturing audio data is simultaneous - it has to capture and write in real time, with very little buffer (a few K only) and without interruption.

    Having the external DVD on Firewire doesn't take any bandwidth except when the DVD is actively pushing data. Because the DVD drive
    1) has a 2 - 8 Mb buffer, and
    2) has a write rate many times slower than the hard drive, and
    3) your DVD burning software also uses a buffer in RAM;
    I don't see much of a bandwidth issue at all. It can happen in sequential chunks quite happily.

    Plus FireWire is much more efficient about data transfer than USB2. As you have discovered, USB takes the bottleneck and moves it to the processor.
     
  8. brap thread starter macrumors 68000

    Joined:
    May 10, 2004
    Location:
    Nottingham
    #8
    OK, sure. I'm not saying it won't work, but... well, it's not an option anyway. I'll take your word for it, what with never having more than one Firewire device hooked up at once.
    Oh, that I knew. USB2->IDE adapters were just so much more... available.
     
  9. TrenchMouth macrumors 6502

    Joined:
    Nov 21, 2002
    #9
    well then...to get back to your point...it is not much of a surprise to most here that your CPU usage would rocket like that during the burning process. That's just the way it is with USB, at least in my experience.
     

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