Upgrade to 6.0

[Rick Stevens]

On 11/11/2010 05:54 AM, Nicosia Gaetano wrote:
> Hi to All,
>
> On my server is installed RHEL 5.5. RedHat has released RHEL 6.0.
>
> How can upgrade from 5.5 to 6.0 ?

I have never done an upgrade where the jump between versions is that
big and I'm not sure it's a good idea.  RHEL5 was based on Fedora 6,
while RHEL6 is based on Fedora 12, and that's a HUGE difference.

Ordinarily, one would boot the media and choose the "Upgrade" option
from the first screen.  Because this is a big technology jump, the
option may not even be offered.

Regardless of what you do, I HIGHLY suggest you back up your system
fully (at least back up all the user's home directories and such).
Once that's done, you can try an upgrade (if the boot disk offers it).
I'd still suggest you do a full reinstall, complete with purging the
hard drives, then restore the user directories and other things you
need from the backup.

If you don't have a backup mechanism, I can offer this shell script:
---------------------------- CUT HERE ----------------------------------
#!/bin/bash
# Back up system to a specific directory given on the command line.
# If no directory is given, it will back up to my 500GB USB drive's
# "Backups" directory with a directory name based on my hostname and
# today's date.
#
# Caveats:
# 1. Make sure you unmount any NFS volumes you may have mounted.  It's
# also suggested that you unmount any non-OS related mounts.  This
# script backs up EVERYTHING, whether it's local on the machine or
# remote mounts.
#
# 2. Make sure the target drive has enough space to hold EVERYTHING
# that remains on your system after unmounting the NFS volumes and
# other non-OS related mounts.  It's a bitter thing when you run out
# of space on the target and have to restart this script.
#
# 3. Things in the /etc/skipdirs.rsync file will NOT be backed up.
# This typically excludes the _contents_ of the /proc, /sys, /dev and
# /media directories, as the contents of those are transient and
# created by the system at startup.  The directories themselves will
# be backed up, but not their _contents_.

# And here we go!
MYHOST=`hostname`
TODAY=`date +%d-%b-%Y`
if [ $# -lt 1 ]; then	# Did we get a directory on the command line?
     TGT="/media/500GB-Drive/Backups/$MYHOST-BackUp-$TODAY"
			# Nope, create one and use it.
else			# Yes, we were given a directory, so...
     TGT=$1		# ...use that name
fi

rsync -avXA --exclude-from=/etc/skipdirs.rsync / $TGT
			# And back things up
---------------------------- CUT HERE ----------------------------------

I'd save the lines between the "CUT HERE" lines to a file, say
/usr/local/bin/backupsys, and "chmod 755 /usr/local/bin/backupsys" to
make it executable.

The "/etc/skipdirs.rsync" file mentioned in the script contains
entries, one per line, to skip while backing up.  My version contains:

	/proc/*
	/sys/*
	/dev/*
	/media/*

Note that this will backup the directories themselves but not their
contents.  A restore from this backup would recreate the directories
but let the system recreate the contents as it normally would.

To run the backup script, become the root user and:

	# /usr/local/bin/backupsys [/path/to/desired/backup/directory]

Hope that helps.  Again, I'd do a full reinstall.  This is a significant
technology jump.
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- Rick Stevens, Systems Engineer, C2 Hosting          ricks at nerd.com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
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-                 IGNORE that man behind the keyboard!               -
-                                                - The Wizard of OS  -
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