migration rhel 6 to 7

Latest response

Hi,
I am required to migrate from rhel 6 to thel 7.
What are the steps if i not use preupgrade-assistance and rhat-upgrade-tool?

  • take backup of all file systems in rhel6
  • make a list with all the settings in system (network,/etc files for services,so on)
    -install rhel 7
    -configure those settings on /etc on network,selinux.

what else?

is the way with preupgrade-assistance and rhat-upgrade-tool best practice?

when i bring back databases i.e oracle database from backup is safe to restore with tar the database files(supposing that i backup every file system with tar)?

Responses

Hello Marius,

EDITED for clarity (hopefully)

Welcome here :)

What's in my post here?

  • A recommendation that Christian Labisch also made concisely below (build a fresh system, export the data and ingest to the new system). I went into more detail, yet the point Christian made is concise.
  • A few possible methods to approach this if you really must take this risk
  • Some info on what we've seen how this goes.

This link has the overall method to upgrade from RHEL 6 to RHEL 7 Please see this article https://access.redhat.com/solutions/21964 which highlights much of what you wish to do.

To reduce risk, make a complete backup of your data, and have the ability to restore it to a fresh new database Please do make a total backup of your Oracle database following their backup recommendations at Oracle's website. Be prepared to be able to restore the database to a fresh new system in case the upgrade fails. In fact, consider having another system that has an active-running duplicate instance of your database before proceeding, just in case.

WARNING: RHEL major upgrades from 6 to 7 can go fine for the OS, but not necessarily 3rd party sofrtware Generally speaking, upgrades from RHEL 6.10 to a supported version of RHEL 7.x goes well for core Red Hat services/functions - this is a carefully worded statement, because the things that generally go not-well are the third-party software. So sadly, there is not a guarantee that your Oracle database will subsequently be compatible with the upgrade and function as expected with the upgrade process.

IN A NUTSHELL: Seriously consider loading a fresh RHEL 7 system, export the data from the old server to the new fresh system!! There is less risk if you load a fresh separate system, export the old data and import it to a fresh new system with a new Oracle instance.

  • This way, you do not lose your currently-functioning RHEL6 Oracle database as a result.
  • Then "burn in" your RHEL7 Oracle Database for a couple of months verifying function/storage/access/capability before eliminating your still-functioning Oracle RHEL6 Database system.

IF your system is virtual ,take a snapshot first If possible, if your system is virtual, shut off your database, then do VMware snapshot (if VMware/RHV) and even clone the system prior, then you can revert to a snapshot if it goes poorly. This also applies if you do a P2V mentioned below.

P2V (Physical to Virtual) Minimize risk, give yourself more chances to do an upgrade from RHEL 6 to 7 If the system is physical, highly consider doing a P-to-V (physical to virtual) clone your physical system to a virtual system (like VMware). Then you can attempt your upgrade from RHEL 6 to RHEL 7 in a virtual instance. This way you can have "multiple attempts" for your upgrade from RHEL 6 to 7.

Regardless what you do, please backup your database in a safe separate location. I can't over-emphasize the importance of a sound backup of your Oracle Database following the Oracle best practices such that you can import to a fresh, new Oracle database running on RHEL 7 (or at minimum another RHEL 6 system as a backup/spare) so you do not lose your capability.

I'll post some other discussions within this forum - it will take a bit to harvest these out.

Please see the link I posted above as an initial starting point as well.

Kind Regards,
RJ

Hi Marius,

A short recommendation for "best practice" : Backup your data - perform a fresh system installation - restore back the data. :)

Regards,
Christian

Thanks Christian - you summed up much of what I said in a tidy sentence :)

Regards,
RJ

You're welcome, RJ ! :)

My initial reply was edited hopefully for clarity.

Thank you, RJ ! Your initial reply was good and clear before as well - and the details you provide are very useful. :)

Regards,
Christian

hi, in root disk migration case after i backup data and i installed a new rhel 7,i need to restore back the config files in /etc ,to import firewall,import selinux and if the node is part of cluster to install the cluster and import the configuration.right?

Hi Marius,

Regarding /etc I wouldn't recommend to import files from the old RHEL 6 system, but rather edit these config
files manually. Too many things have changed. Same is valid for firewall and SELinux. Importing databases and
other personal data is another thing. Well, that is my recommendation derived from my experience at least ... :)

Regards,
Christian

Hi, In rest what i written about cluster case is ok?

Hi Marius,

It very much depends on your specific setup, so it's hard for us to give you a proper advice. :)

Regards,
Christian

Hi Hinton i appreciated your reply.Christian thank you.

You're welcome, Marius ! :)

We wish you well with this Marius

Not to be obnoxious, but please make sure you have backed up your database. It is good to "tar up" /etc among other directories for later reference (as Christian said, do not take the contents of /etc from the old system and place in the new, that would cause very severe issues)

tar -cvf /root/etcbackup.tar /etc

Again, this is just for reference, do not copy things from that to the new /etc on the new system.

Regarding SELinux, it may be good to go to youtube and look up "selinux for mere mortals" here is a link

Regards,
RJ

tar --selinux -cvf /root/etcbackup.tar /etc

saves the selinux contexts too.

Good suggestion Jan ! :)

Wow, even better - I love that example and shall use that!

Thanks!
RJ