CentOS 6U6 na CentOS 7

Ja na mašini imam CentOS 6U6 i razmišljam da pređem na najnoviju verziju CentOS 7.
Dakle moja razmišljanja na tu temu.
Before you do anything, you should update all your packages to the newest versions to avoid any problem later on.
# yum -y update
# reboot
1. Evo šta može da predstavlja problem (link):
Several system-critical packages are of a higher version number in CentOS 6.6 than they are in CentOS 7.
2. Zgodna alatka koju treba pustiti pre bilo kakvih daljih pokušaja (link) :
Preupgrade Assistant can be run on a system with no harm: preupg just analyses the system and gives hints what to look out for during an upgrade without performing any tasks.
Preupg je RHEL alat, i ne instalira se sa standardnih CentOS repozitorijuma, pa se mora dodati novi repositorium.
Evo kako se pribavlja (dobar link) :
# vi /etc/yum.repos.d/upgrade.repo
Place the following entries in it.
[upgrade]
name=upgrade
baseurl=http://dev.centos.org/centos/6/upg/x86_64/
enabled=1
gpgcheck=0
Install the following packages :
# yum -y install preupgrade-assistant-contents redhat-upgrade-tool preupgrade-assistant
3. Evo još nekih paketa koje bi trebalo instalirati pre nego što se krene dalje :
# yum -y install openscap pcre-devel libxml2-devel libxslt-devel m2crypto python-simplejson mod_wsgi
4. Posle ovoga pustiti alat. Paziti, to može prilično da potraje (i do 30min).
# preupg
Preupg tool doesn’t do the actual upgrade.
Please ensure you have backed up your system and/or data in the event of a failed upgrade
that would require a full re-install of the system from installation media.
Do you want to continue? y/n
…..
Exit Codes meaning :
PASS: Everything is good
FAIL: something goes wrong, may have to do with compatibility problem
FIXED: incompatibility was detected, but there are solutions to fix by running postupgrade.d scripts after the upgrade.
INFORMATIONAL: information for admins
NOT_APPLICABLE: some packages are not installed on your system but should be checked
ERROR: means there are errors in the preupgrade-assistant framework (you don’t need to worry about this)
4a. Dodati repozitorijum i ključ za CentOS 7 :
# export http_proxy=”http://10.10.10.94:8080″
# export https_proxy=”http://10.10.10.94:8080″
# export ftp_proxy=”http://10.10.10.94:8080″
Ovakvo proxy setovanje važi samo dok je otvoren dati terminal, i samo za taj terminal…..
Provera :
# env | grep -i proxy
http_proxy=http://10.10.10.94:8080
ftp_proxy=http://10.10.10.94:8080
https_proxy=http://10.10.10.94:8080
# rpm –import http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-7

5. Šta raditi kada se jave neke greške
GNOME Desktop Environment fail
Potrebno je odinstalirati Gnome Desktop i onda raditi upgrade :
# yum groupremove “X Window System” or “Desktop”
Check for usage of dangerous range of UID/GIDs
Potrebno je sve korisničke naloge podići iznad UID/GID 1000 (u CentOS 6 je granica bila 500) :
# id velda
uid=500(velda) gid=500(velda) groups=500(velda)
# usermod -u 1001 velda
Ovo može prilično da potraje, pošto se menja na celom disku vlasništvo.
# groupmod -g 1001 velda
# id velda
uid=1001(velda) gid=1001(velda) groups=1001(velda)

Problem je što se kod mene javlja još dosta problema koji zahtevaju akciju, i što bi dosta mojih programa na CentOS 7 postalo neiskoristljivo.
Zaključak : za sada ostajem tu gde jesam.