On Sun, Jul 13, 2014 at 12:01 PM, Timothy Murphy <gayleard at alice.it> wrote: > I'm having trouble installing CentOS-7 on my HP MicroServer. > I've tried with KDE LiveCD and Netinstall (both on USB sticks), > and now I'm going to try with the DVD ISO. > > But I want to be quite sure I can return to CentOS-6.5 > if things go wrong, so I'm wondering what precisely I need to copy > (eg the MBR and a bit more) so that I could get back to things as they were. > Is this documented anywhere? > > Actually, both failed installations did give a boot menu > including the old 6.5 system, > but I'm afraid sometime this might not work, > and I will be cut off from the world. If you don't overwrite your old partitions, you should be able to boot from a 6.x install iso in 'rescue' mode. But, I'd recommend an emergency backup made either with clonezilla-live (a bootable CD) or the 'rear' package from EPEL just on general principles. Clonezilla does a menu-drive disk-image backup that it can put on a local disk, or network share via nfs/samba/sshfs, and knows enough about filesystems to just save the used blocks. Rear builds a bootable iso (using your own system tools) with a script to recreate your partitions and filesystems from bare metal and restore a tar image onto it. Actually the backup method is somewhat pluggable, but tar to an NFS server is the only one I've used. It is probably possible to use a USB drive of if the system is small enough, include it on the bootable iso. A big advantage of 'rear' is that you don't have to take the system down to create a backup - and it is possible but a bit of work to change the filesystem layout before the restore. -- Les Mikesell lesmikesell at gmail.com