I want to install Scientific Linux from USB. I don't know why unetbootin doesn't work but I am not curious to find out: after all, I transferred to Linux from Windows to see and learn the underlying procedures. I format my USB drive to FAT32 and run this command as root:

# pv -tpreb /path/to/the/downloaded/iso | sudo dd of=/path/to/the/USB/device 

While it works for Live-CDs or network installs (that are less than 1GB) it doesn't work for the actual installation DVDs that are about ~4GB. I would be really grateful if anyone can help me fix this problem.

Considering the fact that it works for smaller .iso files, I guess it has to do with the File System, am I correct? What other options do I have?

1 Answer 1


A CD-ROM and USB stick use entirely different methods to boot. For an ISO9660 image on a CD-ROM, it's the El Torito Specification that makes it bootable; for a USB stick, it needs a Master Boot Record style boot sector.

ISOLINUX, the bootloader that is used in ISO9660 CD-ROM images to boot Linux, has recently added a "isohybrid" hybrid mode that uses some clever tricks to create a single image that can be booted both ways.

My guess is that your LiveCDs are actually isohybrid images, whereas the full installation DVDs are not. You may be able to use the isohybrid tool in the syslinux distribution to convert them, as described in the hybrid mode link above.

  • Thanks for the detailed information, I learnt a lot. Applying isohybrid to the .iso gives these two comments: isohybrid: Warning: more than 1024 cylinders: 3482 and isohybrid: Not all BIOSes will be able to boot this device. I am trying to copy the .iso to USB to see what happens.
    – makhlaghi
    Aug 14, 2012 at 6:57
  • Fortunately those errors were not important for my BIOS and it worked excellently. Thanks a lot Jim.
    – makhlaghi
    Aug 14, 2012 at 7:26

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