Re: Fedora upgrade to a new partition



On Sat, 11 Dec 2010, Timothy Murphy wrote:

| Date: Sat, 11 Dec 2010 17:47:50 +0000
| From: Timothy Murphy <gayleard@xxxxxxxxxx>
| To: users@xxxxxxxxxxxxxxxxxxxxxxx
| Followup-To: gmane.linux.redhat.fedora.general
| Subject: Re: Fedora upgrade to a new partition
|
| Joachim Backes wrote:
|
| > having the following question: sometimes it happens that after an
| > upgrade of a Fedora-x to a Fedora-y, the Fedora-y does not run correctly
| > (there may be a lot of reasons for this...). So going back to a running
| > system, but how to achieve this?
| >
| > So my question (or proposal): it would be very helpful if an upgrade
| > could be done to a new partition (including copying all imporant files
| > from the Fedora to be updated). This would save oneself a lot of backups
| > and restores.
|
| I always do exactly that.
| Nb I keep separate /home and /boot partitions,
| which I don't format when upgrading.
| (I choose the Custom Upgrade choice,
| not the disastrously bad default which re-partitions your machine.)

I do something quite similar.

I don't have a separate /boot partition: I keep /boot as part of the
per-version / partition.

I would not have thought that a single shared /boot would work.
Different systems might want to have conflicting files (eg.
/boot/grub/grub.conf).

I have gotten in trouble in a couple of ways:

- dot-files for different releases don't always "get along".

- once (a long time ago) a new Fedora relabeled /home (in the SELinux
sense, I think) and made it impossible for the old Fedora to access.

This was made worse by
+ no big warning signs in the release notes
+ an inscrutable diagnostic (from the old version)
+ the new Fedora didn't support the video card on the machine
so we needed to go back to the old Fedora but it could not
be made to work

I have separate /home partitions for different distros when I have
multiple distros on the same machine. The above problems would surely
be increased if I tried to share /home between distros.

Another issue: how to do booting. What lives in the Master Boot
Record (the first track on the drive)? What lives in each partition's
Boot Record?

There are essentially two ways to do this using GRUB (other
bootloaders are not mainstream Linux approaches on a PC):

(a) one GRUB to boot any system on the disk, or

(b) one GRUB chainloads any other partition: GRUB loads that
partition's Boot Record and transfers control to it. So each
system uses its own bootstrapping.

(c) some mixture of (a) and (b)

- booting MS Windows requires (b) because GRUB doesn't know how to load
Windows.

- GRUB2 almost forces (a) for Linux partitions but gets it wrong.
It forces it because the conventional automatic config-file
generation creates entries of this type for each partition with
Linux.
It gets it wrong because it cannot possibly know what the
requirements are of that partition's Linux (example: kernel flags).

Furthermore, I think that the new standard for partitioning, GPT, only
allows for one boot partition. I don't know how multiboot works
there.


One thing that I don't do, but I should is to copy ssh server keys from
the old system's /etc/ssh files to the new system so folks ssh'ing in
don't get told that the system isn't the one they last used. See
<http://docs.fedoraproject.org/en-US/Fedora/14/html/Deployment_Guide/s2-ssh-configuration-sshd.html>
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