CentOS 6 to CentOS 7 Upgrade Procedure

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(No Transcript)
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• CentOS 7 was released only few weeks after Red
  Hat Enterprise Linux 7, including the
  same exciting features RHEL ships.
• Besides the long awaited Systemd and the right
  now much discussed Docker this release also
  features the possibility to perform upgrades from
  version 6 to version 7 automatically without the
  need of the installation images.
• And although the upgrade still requires a reboot
  and thus is not a live upgrade as such, it comes
  in very handy for servers which can only be
  reached remotely.
• Red Hat has already released and documented the
  necessary tools. The CentOS team didnt have time
  yet to import, test and rebuild the tools but the
  developers are already on it  and they provide
  untested binaries.

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• Please, note Since the packages are not tested
  yet you should not, by any means, try these on
  anything else than on spare test machines you can
  easily re-deploy and which do not have any
  valuable data.
• Do not try this on your production machines!
• But if you want to get a first idea of how the
  tools do basically work, I recommend to set up a
  simple virtual machine with a fully updated
  CentOS 6 and as few packages as possible.
• Next, install the rpms from the CentOS repository
  mentioned above.
• Among these is the Preupgrade Assistant, which
  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.

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• Since I only tested with systems with hardly any
  services installed I got no real results
  from preupg. Even a test run on a system with
  more services installed brought the same output
  (only showing some examples of the dozens and
  dozens of lines)
• sudo 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
• y

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Gathering logs used by preupgrade
assistant All installed packages 01/10
...finished (time 0000s) All changed files
02/10 ...finished (time 0048s) Changed config
files 03/10 ...finished (time 0000s) All
users 04/10 ...finished (time
0000s) ... 042/100 ...done (samba shared
directories selinux) 043/100 ...done (CUPS
Browsing/BrowsePoll configuration) 044/100
...done (CVS Package Split) ... samba shared
directories selinux notapplicable CUPS
Browsing/BrowsePoll configuration notapplicable
CVS Package Split notapplicable ...
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• As mentioned above the Preupgrade Assistant only
  helps evaluating what problems might come up
  during the upgrade the real step must be done
  with the tool redhat-upgrade-tool-cli. For that
  to work the CentOS 7 key must be imported first
• sudo rpm --import http//isoredirect.centos.org
  /centos/7/os/x86_64/RPM-GPG-KEY-CentOS-7
• Afterwards, the actual upgrade tool can be
  called.
• As options it takes the future distribution
  version and a URL to pull the data from.
• Additionally I had to add the option \--force sinc
  e the tool complained that preupg was not run
  previously although it was.
• As soon as the upgrade tool is called, it starts
  downloading all necessary information, packages
  and images, and afterwards asks for a reboot
  the reboot does not happen automatically.

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• sudo /usr/bin/redhat-upgrade-tool-cli --force
  --network 7 -- instrepohttp//mirror.centos.org/c
  entos/7/os/x86_64 setting up repos...
• .treeinfo 1.1 kB 0000
• getting boot images...
• After the reboot the machine updates itself with
  the help of the downloaded packages.
• Note that this phase does take some time,
  depending on the speed of the machine, expect
  minutes, not seconds.
• However, if everything turns out right, the next
  login will be into a CentOS 7 machine

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cat /etc/os-release NAME"CentOS Linux"
VERSION"7 (Core)" ID"centos"
ID_LIKE"rhel fedora" VERSION_ID"7"
PRETTY_NAME"CentOS Linux 7 (Core)"
ANSI_COLOR"031" CPE_NAME"cpe/ocentoscent
os7" HOME_URL"https//www.centos.org/"
BUG_REPORT_URL"https//bugs.centos.org/"
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• Concluding it can be said that the upgrade tool
  worked quite nicely.
• While it is not comparable to a real live upgrade
  if offers a decent way to upgrade remote servers.
  
• Ive tested it with a clean VM and also with bare
  metal, remote server, and it worked surprisingly
  good.
• The analysis tool unfortunately did not perform
  how I expected it to work, but that might be due
  to the untested state or I was not using it
  properly.
• Im looking forward what how that develops and
  improves over time. But, again, and as mentioned
  before dont try this on your own prod servers.