| 
  | writeImageBlankSafe(config,
        rebuildMedia,
        todayIsStart,
        blankBehavior,
        stagingDirs)
   | source code |  Builds and writes an ISO image containing the indicated stage 
  directories. The generated image will contain each of the staging directories 
  listed in stagingDirs.  The directories will be placed into 
  the image at the root by date, so staging directory/opt/stage/2005/02/10will be placed into the disc at/2005/02/10.  The media will always be written with a media 
  label specific to Cedar Backup. This function is similar to writeImage, but tries to implement a smarter blanking 
  strategy. First, the media is always blanked if the rebuildMediaflag is true. Then, ifrebuildMediais false, blanking 
  behavior andtodayIsStartcome into effect: 
  If no blanking behavior is specified, and it is the start of the week,
  the disc will be blanked
  If blanking behavior is specified, and either the blank mode is "daily"
  or the blank mode is "weekly" and it is the start of the week, then
  the disc will be blanked if it looks like the weekly backup will not
  fit onto the media.
  Otherwise, the disc will not be blanked
 How do we decide whether the weekly backup will fit onto the media?  
  That is what the blanking factor is used for.  The following formula is 
  used: 
  will backup fit? = (bytes available / (1 + bytes required) <= blankFactor
 The blanking factor will vary from setup to setup, and will probably 
  require some experimentation to get it right. 
    Parameters:
        config- Config object.rebuildMedia- Indicates whether media should be rebuilttodayIsStart- Indicates whether today is the starting day of the weekblankBehavior- Blank behavior from configuration, orNoneto use 
          default behaviorstagingDirs- Dictionary mapping directory path to date suffix.Raises:
        ValueError- Under many generic error conditionsIOError- If there is a problem writing the image to disc. |