Debilitating disk activity level on Mac OS X 10.6.8

Discussion in 'macOS' started by rhimbo, May 20, 2012.

  1. rhimbo macrumors member


    Jun 21, 2009
    Hi folks,

    Mac Book Pro
    Mac OS X 10.6.8, Snow Leopard, 2.5 GHz Intel Core 2 Duo
    4 GB RAM, 667 MHz DDR2 SDRAM,

    For the past week or so I have been seeing inordinately high disk activity. That is, I'm not running anything except Firefox 12.0. I have a few apps open but nothing running in the background... no compiles, no IDEs running, etc.

    I've attached screen shots of System monitor showing the disk activity and CPU tabs, and I've also attached the output of "ps -ax" captured just a few moments before posting this note.

    I've searched the forums for similar posts but all refer to performance problems related to a specific process or application. I am having difficulty associating the high disk activity with a particular process or thread.

    I don't see high CPU activity at all. And I don't believe I have a virus as I have not clicked on any links in unknown emails. I have not upgraded Adobe Reader in response to a pop up (can't recall the name of that virus that made news a few weeks ago).

    Can anyone shed light?

    Many thanks....

    Attached Files:

  2. rhimbo thread starter macrumors member


    Jun 21, 2009
    New information regarding this issue

    Hello again everyone,

    OK, this is embarrassing....

    Now the disk activity has subsided to almost nothing. Pages load with lightning speed in Firefox again. Writes to files are fast, etc.

    So the disk activity has been high for the past 3 days -- to the point I could hardly use my browser -- waiting 30 seconds for a page to load. Suddenly it has returned to normal.

    For my own edification, I would much appreciate if someone notices and comments on what the cause was. I have not rebooted my system in months. I'm wondering if the high disk activity was a Mac OS X process that does indexing or something similar. I just didn't (and don't) know what process to look for or how to glean the "ps" output, "top" output and Activity Monitor output to determine which process was doing the high level of disk writes.

    Many thanks....
  3. Intell macrumors P6


    Jan 24, 2010
    My iMac does this sometimes. The thing that's causing it is FireFox clearing out its cache. I don't know why it writes to the disk to clear out the cache, but that's what it is. I've also never had it last more then five minutes. You can use fseventer to see exactly which files are being written to.
  4. rhimbo thread starter macrumors member


    Jun 21, 2009
    Thanks for the info...

    Ah, that's interesting. I wonder if Firefox zeros out sectors for security? I don't know why else clearing its cache would precipitate so much disk activity. If not zeroing out sectors, the only writes are updates to inodes in the file system.

    I will get fseventer for next time I notice the high disk activity!

    Many thanks again.....

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