Martin Minka wrote:

Hello, is there a way to boot CentOS 4.5 from USB flash key in rescue mode ? The prefered solution would be to have booting part of CentOS started by SysLinux and download the content of CD1 from a network server (HTTP), like Anaconda is able to use command "method".

It is possible to do this, but is very shaky because it very much depends on your bios support for booting from a usb key.

The better way to do this is to just either setup a PXE boot server with support for this vmlinuz/initrd.img:

http://mirror.centos.org/centos/5/os/i386/images/pxeboot/

(you pick your version for "5", and your arch for "i386" ... then download off the mirror servers ... then add a "linux rescue" when booting from that on PXE.

===OR===

you can put those vmlinuz/initrd.img files on all your servers (somewhere in /boot) and create a grub entry on all the machines that have the kernel line:

kernel /path_to/vmlinuz rescue initrd /path_to/initrd.img

You will then need to have a tree to point to via a network install.

This method works on all centos servers regardless of whether the USB key can be booted from or not.