Explanation/Reference:
Explanation:
Mirror style backups without compressions are good to use when you are backing up a lot of files with compression already applied them. For example, music files in mp3 or wma format, images in jpg or png format, videos in dvix, mov, or flv format, and most program install or setup files are already compressed.
If you include these files in a normal backup that applies compression you will often notice it will be very slow, and you will gain very little extra compression by doing so. It is best to set up separate backup jobs for compressed files and non compressed files. If your backup program supports include and exclude filters they can be used to either automatically select or deselect the compressed files respectively.