Chapter 2. Preparing a RHEL 6 system for the upgrade

This procedure describes the steps that are necessary before performing an in-place upgrade to RHEL 7.

Prerequisites

You have verified that your system setup is supported for an upgrade from RHEL 6 to RHEL 7. See Planning an upgrade for more information.

Procedure

Ensure that your system is registered to Red Hat Subscription Management (RHSM).
If your RHEL 6 system is registered to Red Hat Network (RHN), you must migrate to RHSM. See Migrating from RHN to RHSM in Red Hat Enterprise Linux for details.
Ensure that you have access to the latest RHEL 6 content. If you use the yum-plugin-versionlock plug-in to lock packages to a specific version, clear the lock:
```
# yum versionlock clear
```
See How to restrict yum to install or upgrade a package to a fixed specific package version? for more information.

Enable the Extras repository, which contains necessary packages for a pre-upgrade assessment and an in-place upgrade.

For the Server variant on the 64-bit Intel architecture on server edition:

# subscription-manager repos --enable rhel-6-server-extras-rpms --enable rhel-6-server-optional-rpms

For IBM POWER, big endian systems:

# subscription-manager repos --enable rhel-6-for-power-extras-rpms --enable rhel-6-for-power-optional-rpms

For the IBM Z architecture:

# subscription-manager repos --enable rhel-6-for-system-z-extras-rpms --enable rhel-6-for-system-z-optional-rpms

For the HPC Compute Node variant on the 64-bit Intel architecture:

# subscription-manager repos --enable rhel-6-for-hpc-node-extras-rpms --enable rhel-6-for-hpc-node-optional-rpms

Install the Preupgrade Assistant and Red Hat Upgrade Tool:
```
# yum install preupgrade-assistant preupgrade-assistant-el6toel7 redhat-upgrade-tool
```
Note
If your system does not have internet access, you can download the Preupgrade Assistant and Red Hat Upgrade Tool from the Red Hat Customer Portal. For more information, see How to install preupgrade assessment packages on an offline system for RHEL 6.10 to RHEL 7.9 upgrade.
Remove all unsupported package groups:
```
# yum groupremove group_name
```
Replace group_name with each unsupported group name. To locate a list of installed group names, run yum grouplist.
Check Known Issues and apply workarounds where applicable. Especially, on systems with multiple network interfaces:
1. If the system has static routes configured, replace the static route file. See redhat-upgrade-tool fails to reconfigure the static routes on the network interfaces, preventing the upgrade to happen for more information.
2. If the system runs NetworkManager, stop NetworkManager prior to running the upgrade tool. See redhat-upgrade-tool fails to reconfigure the network interfaces, preventing the upgrade to happen for more information.
Update all packages to their latest RHEL 6 version:
```
# yum update
```
Reboot the system:
```
# reboot
```
Back up all your data before performing the upgrade to prevent potential data loss.

Verification steps

Verify that you are registered with the Red Hat Subscription Manager:
```
# yum update
```
The Loaded plug-ins: entry must contain subscription-manager.
Verify that only supported package groups are installed:
```
# yum grouplist
```

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