Hi, since the USB memory stick is getting cheap these days, I am thinking of making a custom-make USB bootdisk myself to help virus checking of Windows system using ClamAV. I dun like to use normal CD-based bootdisk since I can't update the virus definitions that way.

I know there are a lot of instructions that can be found around the web, but I just want some answers to some general, non-distro-specific questions. Hope you bear with me. :-)

1. What is the difference amongst the bootable ISO images of floppy, CDROM and USB drive? Are they all the same?

2. Can we simply install a distro into a USB thumb drive and use it as USB bootdisk? AFAIK, Live-CD like Knoppix compresses its image file so it takes time to uncompress. If we install a distro straight into a USB drive, I guess this will save some time uncompressing the files. Is this true?

That's all for now.

Thanks a lot :-)

check out www.slax.org there is a good forum with several explanations on how to install a bootable linux OS on a USB drive.

But it only works if you can boot from USB in the BIOS. If not you'll have to use a CD or floppy to boot from and tell it to boot from the USB drive.

1. They are not all the same. In fact, most distros that run on floppies aren't even isos. They are just tgz files that are read when booted. There are many, many, many distros made for floppy discs. Some even have GUIs, believe it or not. CDROMs use isos, but I think USBs, like floppies contain the uncompressed files in order to boot.

2. kinda answered this in one...

Let me try it this way.

An iso by definition is a filing system to iso9660 CD booting standard. It comes in a single file and cannot make any sense anybody in a hard disk. It can only be read if mounted on a loop back device to simulate a CDrom.

An bootable iso file will have a special boot loader packaged inside. This boot loader can only boot from a CD and the de facto standard boot loader used by everybody is isolinux, although a special version of Grub is also used. Therefore if you manage to open up an iso file it will not be bootable from a hard disk, a floppy or a USB device. You need to substitute isolinux with another hard disk-based boot loader.

As a file you can move an iso from media to media.

The following threads are useful if you intend to boot iso directly from a hard disk or USB device.

(1) (2) and (3)

In one syllable or less, how do you make either the Simply Mepis Live CD or the Fedora 8 live CD bootable from a thumb drive?

All attempts that I have made have failed. I have no problem making bootable CDs. Copying doesn't work either.

Are there any differences with external hard drives?