Dumped on by MMON (30+ GB worth)



  • To get more space on my C drive and address seemingly slower disk operations, some 24 hours or so were spent uninstalling programs, deleting files, backing up files, defragmenting multiple times, doing a full Ghost of my machine (which failed with a general exception 14 hours into it), and repartitioning my hard disk (among other things).  After the initial lengthy effort, life seemed good with more than 15 GB free space on C, and more that followed.

    Within only a few hours of uptime, I am stunned by the "running low on disk space" tray message that Windows pops up.  Knowing I did nothing to account for the loss of 15+ GB of space in a few hours, I suspect a virus and begin scanning the drive for recently modified files, and checking process manager for disk I/O activity. 

    I find the "virus"... ORACLE!  🙂  The various "dump" folders in c:\oraclexe\app\oracle\admin\XE have nearly 30 GB of recently modified trace files there, almost 1,000 files in all, some of which were over half a gig each.  Many of the .trc files have "mmon" in the filename so I did some research.  Apparently it is new with 10g and performs various automatic monitoring, diagnostics, snapshots, statistics, performance checks and so forth.

    First of all disk space is not that cheap, even for a more full-blown Oracle install on a server, much less a lite personal edition like XE for desktop use.  Secondly, I certainly did not modify any configuration settings and for this to be default behavior seems excessive (not sure XE even provides much).  If the default monitoring process can be that resource intensive, one might hope it would be less hidden and more easily configurable. Sorry, I think I just had a SQL Server flashback there; this is Oracle, and the day it has intuitive tools and easy administration is the day it needs a new name. I also have to wonder how much that level of instrumentation might affect the database server itself.

    After all the grief and work for not, I am certainly keeping a closer eye on my hard disk space now and have stopped the Oracle services from automatically starting.  However my Oracle administration paranoia level is at an all time high and I may very well be scarred for life.

    That's a dump alright

     


  • Winner of the 2016 Presidential Election

    If you're looking to find where your disk space is going, then you should use a tree map.  Konqueror has them built-in on Linux.  For Windows, I use a shareware application called SpaceMonger.  It lets you see your file structure something like this:

    So, larger files look visually larger. Then you can zoom in, or hide files you know you can't get rid of, and find the excess. I'm always amazed at how much junk I find to delete.



  • so what was the error in the mmon trace files?



  • @joe.edwards@imaginuity.com said:

    If you're looking to find where your disk space is going, then you should use a tree map.  Konqueror has them built-in on Linux.  For Windows, I use a shareware application called SpaceMonger.  It lets you see your file structure something like this:

    So, larger files look visually larger. Then you can zoom in, or hide files you know you can't get rid of, and find the excess. I'm always amazed at how much junk I find to delete.

    Supernifty.

    There's a program called Sequoiaview that does the same mapping thing, but applies colour to file extensions, and shows the file/path in a tooltip. Less extensive stats, but totally free.


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