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.
- 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.
- 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.
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
- 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? 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?
- 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?
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.
And I'll try a couple of your suggestions first, like not installing the boot-loader.