1. Welcome to the new MacRumors forums. See our announcement and read our FAQ

Mysterious disk writes

Discussion in 'PowerPC Macs' started by TrailerTrish, Aug 20, 2012.

  1. macrumors member

    I recently added another 2tb Western Digital MyBook external USB drive to my PowerMac MDD, the sixth such external drive on my system, and I'm seeing some strange behavior from it that I have not observed at all with the other drives.

    It's little white light flashes a lot, on and off, when I'm not writing anything to it or reading anything from it. So I start up Activity Monitor, and I'm seeing writes to disk and reads from disk as that light flashes when I'm not doing anything at all on disk, which I find most curious.

    Now I can see that there would be a certain amount of device polling going on, and that makes sense, but what is being written to that disk when I'm not even using it, and what's doing those disk writes? I have no idea, and it appears to be happening on this new drive, but not the others, and I can't imagine why. There are about 700 movies on that drive, but no program files at all.

    This is pretty weird. Anyone know what might be going on?
  2. macrumors 6502

    What applications (If any) are running? Whether they are background processes or programs you're actively using?
  3. macrumors 68040


    It could be Spotlight indexing or Time Machine. Check processes in Acivity Monitor as Daedalus said when you see disk activity on WD. Choose "All processes" in "Show" bar. Do you see any changes in available disk space?
  4. macrumors newbie

    Agreed with previous poster. This is most likely a indexing if it's bothersome you can disable spotlight.
  5. macrumors G5


    It probably is indexing...It should eventually stop unless it's re-indexing the drive persistently...If so, as posted it can be disabled.
  6. TrailerTrish, Aug 21, 2012
    Last edited: Aug 21, 2012

    macrumors member

    I tried to quit the Spotlight process, but it will just not go away, even when force quit, it just keeps coming back. How do you disable it? I never use it.


    Well I've been watching this in Activity Monitor, and it seems that when the writes to that disk happen it's always iTunes using the most CPU. I can find no files on that disk other than what I put on it, and why would iTunes be writing to it? There are no files associated with iTunes on that drive at all, no music, no files there in my iTunes media library.

    Here's what I'm seeing:

  7. TrailerTrish, Aug 21, 2012
    Last edited: Aug 21, 2012

    macrumors member

    Well when I set this disk up it asked if I wanted to use it with Time machine and I said no, so it shouldn't be Time Machine accessing it, but you never know really.

    I have tried to disable Spotlight using the instructions I found online, but the commands wouldn't work, and I cannot find any Spotlight.plist at all on my system. Pretty odd. I'm running Leopard BTW.

    I just tried to change the permissions on that disk, which were

    Macuser (Me) read/write
    (unknown) read/write
    Everyone read only

    So it appears that "unknown" can read and write to my disk, which really doesn't seem to me like a good thing at all, and I cannot change that permission. Bummer in the Summer!
  8. macrumors 68040


    If you're running 10.5, you need to use method described there: http://tech.karbassi.com/2009/05/12/how-to-fully-disable-spotlight-in-leopard/ to disable Spotlight. 10.4 uses other commands for that purpose.

    Another way is to leave your MDD on for couple of hours to let Spotlight fully index your WD drive.
    BTW, if you trying to trace all active processes you need to view "All processes" instead of "My processes".

    Attached Files:

  9. macrumors member

    Might want to try the Power of UNIX(tm) :)

    If something is hitting that disk it stands to reason that there are open files on the disk, if you drop to a terminal try running


    Which will return a list of all currently open files on the computer. The first column will be the process that holds the file lock, and the last column will be the list of files, if you have the drive mounted to /Volumes/Bob (for example) you should be able to trim the list down to just that volume by running it though grep.

    lsof | grep Bob

    will just return entries that have Bob in them (it is case sensitive, grep -i Bob will return the case insensitive version)

Share This Page