11 Replies Latest reply: Sep 23, 2012 9:47 AM by WZZZ
neus32 Level 1 Level 1

My HDD is constanty writing without any activity on my part. Excluding the HDD from Spotlight search or disconnecting the machine from the net makes no difference. Seems to be a common problem among users but haven't found a fix. Help much appreciated.



iMac, OS X Mountain Lion (10.8.1), 2,66 Ghz Intel Core i5, 4 GB DDR3
  • BDAqua Level 10 Level 10

    Hi Stefan,


    Open Console in Utilities & see if there are any clues or repeating messages when this happens.


    See if the Disk is issuing any S.M.A.R.T errors in Disk Utility...



  • baltwo Level 9 Level 9

    Running Time Machine?

  • neus32 Level 1 Level 1

    Hi baltwo!


    Yes - but makes no difference whether TM i on or off.



  • neus32 Level 1 Level 1

    Hi BDAqua!


    No messages whatsoever. When checking the HDD with the disk utility - it states that the disk is ok.



  • BDAqua Level 10 Level 10

    Open Activity Monitor, Show:>All Processes, sort on CPU%, see if anything using too much CPU%, see if we can spot the process using it.

  • neus32 Level 1 Level 1

    Hi BDAqua,


    Looking at activity monitor was in fact the first thing I did - but while there's a lot of disk activity, there seems to be very litte CPU involvement.


    The kernel_task is the most activite one (beside activity montor task of course) but mostly in the range between 0,3 and 1,5%. Other active processes are almost always below 1%. I'm not sure what to comsider as "too much" in this context?



  • WZZZ Level 6 Level 6
    Mac OS X

    Open Terminal in Utilities and enter


    sudo fs_usage


    Hit return, after which you will be prompted for your admin password. You won't see it as you type it in. And you will be given a warning, then hit return again.


    You will have to scroll down -- use the down arrow -- looking for all the writes and which process is making them. There will be a lot to look through, but this may give you a clue.


    To quit, enter Control-C.

  • BDAqua Level 10 Level 10

    Great suggestion!

  • Allan Jones Level 7 Level 7

    Just to be sure, did you make the change in Activity Monitor that BDAqua suggested? Makes a huge difference as, by default, AM shows only a limited number of processes.


    Any third-party "pay for" anti-virus or security software running?


    Perchance do you have the game "Prey"? Its demo caused my MacBook Pro to continuously write to system.log, ballooning that file from normal 200-300k to over 65MB. The game did not have to be running for it to act out.

  • neus32 Level 1 Level 1

    Hi WZZZ and BDAqua,


    My HDD have stayed rather calm for a number of days, but is now chugging along again. I did run the sudo fs_usage and these are the processes I see (the two first are the most frequent):












    For Allan Jones: Yes- I'm viewing all processes in activity monitor.



  • WZZZ Level 6 Level 6
    Mac OS X

    Searching, hamachid appears to be related to Logmein. Do you have that?


    mdworker and mds are both Spotlight. For that, try reindexing Spotlight.