|
Forum: UltraISO Topic: 1Gb ISO file size on disk, 544Mb on CD? started by: timg11 Posted by timg11 on Aug. 07 2008,09:59
I recently downloaded an Xubuntu distribution. The file size of the .ISO file on disk is about 1Gbyte. When opening the ISO in UltraISO, it reports a total size of 544Mbytes. Why is the file size on disk so much larger than the size when burned onto a CD? Is there a lot of "redundant" information in the ISO file? I tried compressing within UltraISO using fast compression, but the size was barely reduced - maybe 10-20Mbytes. Out of curiosity, I used Winzip to compress the ISO, and also saw only 10-20Mb reduction to the 1G file. The properties show the file system is both Joliet and Rockridge - does that mean the data is duplicated in the ISO file, once for each file system? Posted by xoben on Aug. 08 2008,00:38
Just checked download site of Xubuntu ( < http://mirror.anl.gov/pub/ubuntu-iso/CDs-Xubuntu/8.04/release/ > ), the size of xubuntu-8.04.1-desktop-i386.iso should be 544MB.
Posted by timg11 on Aug. 08 2008,15:04
I saw the size listed on the site. But the file on my disk after downloading is 0.99 GB (1,068,118,016 bytes). So it starts out as 544MB on the remote site, and becomes .99GB when on my disk. Can anybody explain why the downloaded file is about 2X the size of the actual ISO content size? |