CAUTION:  Note  that  shred relies on a very important assumption: that
       the file system overwrites data in place.  This is the traditional  way
       to  do  things, but many modern file system designs do not satisfy this
       assumption.  The following are examples of file systems on which  shred
       is not effective, or is not guaranteed to be effective in all file sys‐
       tem modes:

       * log-structured or journaled file systems, such as those supplied with

              AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.)

       *  file  systems  that  write  redundant data and carry on even if some
       writes