Why do my disks spin up?

Discussion in 'macOS' started by bigwig, Jan 20, 2011.

  1. bigwig macrumors 6502a

    Joined:
    Sep 15, 2005
    #1
    I have "put hard disks to sleep when possible" set in my Energy Saver preferences. My external FireWire drive does indeed sleep, but it spuriously spins up ever few minutes for no discernible reason. I did not launch any application or system service that would access the drive. Why is it spinning up?
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    Are you using Finder or any app where you open or save files? If so, that causes it.
     
  3. bigwig thread starter macrumors 6502a

    Joined:
    Sep 15, 2005
    #3
    I was not using Finder on a directory on that drive nor saving any files to that drive.
     
  4. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #4
    It doesn't matter if you're trying to access that drive or not. When you open a Finder window, or search or try to open or save a file through the open/save dialog box, all mounted drives will spin up so they're available to the operation, whether you select them or not. Finder doesn't know which drive you plan to use, so it makes them all ready. If you don't want it to spin up in these cases, unmount the drive.
     
  5. bobr1952 macrumors 68020

    bobr1952

    Joined:
    Jan 21, 2008
    Location:
    Melbourne, FL
    #5
    I can be somewhat annoying but you'll get used to it. :)
     
  6. bigwig thread starter macrumors 6502a

    Joined:
    Sep 15, 2005
    #6
    That's silly. The driver should take care of that. Oh well.
     
  7. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #7
    How can the driver "take care of that"? The driver doesn't know which drive you're going to select, any more than Finder can.
     
  8. bigwig thread starter macrumors 6502a

    Joined:
    Sep 15, 2005
    #8
    The driver knows whether the disk it is attached to is being selected, because an I/O request to that drive has been initiated. There is no need to know in advance whether a drive will be selected, nor is there any need to spin up drives in anticipation of being selected. Drivers should keep drives spun down until they are actually selected, then spin them up.
     
  9. baummer macrumors 6502a

    Joined:
    Jan 18, 2005
    Location:
    Southern California
    #9
    This has been happening since 10.4 if not earlier. It's annoying but you do get used to it. Some external drives work better than others. I've found the delay is slightly longer when using USB external drives.
     
  10. mjsmke macrumors 6502a

    Joined:
    Mar 2, 2010
    Location:
    UK
    #10
    I set all my drives never to sleep. Obviously when i put the Mac to sleep then they do.
     
  11. exabytes18 macrumors 6502

    Joined:
    Jun 14, 2006
    Location:
    Suburb of Chicago
    #11
    I agree. You can be somewhat annoying, but I'm used to it by now. :)
     
  12. Damo01 macrumors regular

    Joined:
    Feb 11, 2010
    Location:
    Australia
    #12
    it could one of system's process such as spotlight's mds or mdworker, but i could be wrong.
     

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