On 07/15/2014 05:22 AM, Timothy Murphy wrote: > Ted Miller 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? > >> You asked what to keep to be able to boot C6. From your narrative, it >> seems that the legacy grub boot for C6 is already gone (blown away) by >> your >> C7 install. I haven't figured out enough about grub2 to be able to tell >> you how to preserve your current grub2 configuration, but here are some >> possible ways to keep C6 accessible: > > Thanks very much for your comprehensive reply. > >> 1. The Super Grub2 Disk from seems to be >> pretty good at finding any and all possibilities for booting using new and >> old versions of grub. > > I've downloaded this and will try it if necessary. > >> 2. If you are reinstalling into exactly the same location as your previous >> C7 attempts (same devices for boot and root), just don't let the installer >> update the boot information. Since you know it boots both versions now, >> it should still boot both versions after the install. > > Yes, I'll try that - though I don't remember being asked > if I wanted to update the bootloader - I probably missed it. Now that you mention it, I don't remember seeing it in C7 either. Maybe on the page where you do disk partitioning? >> Not knowing what your installation problem is, I can't tell (and you may >> not be able to tell either) if anything is wrong with your boot >> information, or if that is OK. > > I'm pretty sure it gets through the code in the boot, > since it says > [OK] Reached target Initrd Default Target > >> 3. From C3, install legacy grub onto a USB stick, which would allow you to >> boot directly to C6, without any requirement for anything to be on a hard >> drive. > > I'm not sure what you mean by C3? Should have been C6. > I see that my CentOS-6.5 system has entries in grub/grub.conf > which don't seem very old (January this year). > > I did wonder if one can in fact use grub with CentOS-7, > since it seems to create an empty (almost) /boot/grub/ folder? > >> 4. It is also possible to set up a CD that will boot your computer, but I >> don't remember the details of that. > > Not quite sure what you mean by this? It is possible to burn a CD with grub or grub2 files on it, which will allow you to get to one (or both) of your installs. Like a live CD, but all it does is direct the boot process to your hard disk. (Don't ask me the details -- did it once with a floppy, but never with a CD). >> Hope one of these, or something someone else chimes in, will help you. >> Also hope you get the C7 install figured out. So far I have only done it >> from DVD, and those went well for me. > > I've found a second hard disk (from an old server) and put that in, > so I'll be able to experiment with that, > without worrying about what it does to my current CentOS-6.5 system. > > Also I used to use the old grub interactively - > I'll see if it is still possible to do this with grub2. Yes it is, but you have to use the new syntax. > And I'll try a couple of your suggestions first, > like not installing the boot-loader. Hope it works, Ted Miller