Upgrading SAP environments from RHEL 7 to RHEL 8

Procedure

1. Complete system-specific setup.

   1. Preparing non-cloud or BYOS cloud systems
      

      1. Register and subscribe the system to a Red Hat repository source. If you use Red Hat Satellite, make sure that both RHEL 7 and RHEL 8 repositories are available and synchronized with the latest updates. Enable the following repos for the activation key:

         rhel-7-server-rpms
         rhel-sap-for-rhel-7-server-rpms
         rhel-sap-hana-for-rhel-7-server-rpms
         rhel-7-server-extras-rpms
         rhel-8-for-x86_64-baseos-rpms
         rhel-8-for-x86_64-appstream-rpms
         rhel-8-for-x86_64-sap-netweaver-rpms
         rhel-8-for-x86_64-sap-solutions-rpms

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      2. Check and confirm that your RHEL 7.9 system has the normal repositories enabled. Also, enable the rhel-7-server-extras-rpms repository, which contains the required upgrade tools:

         # subscription-manager repos --disable='*' \
         --enable="rhel-7-server-rpms" \
         --enable="rhel-sap-hana-for-rhel-7-server-rpms" \
         --enable="rhel-7-server-extras-rpms"

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         If you are also using the SAP NetWeaver repository (rhel-sap-for-rhel-7-server-rpms), enable that one as well:

         # subscription-manager repos --disable='*' \
         --enable="rhel-7-server-rpms" \
         --enable="rhel-sap-for-rhel-7-server-rpms" \
         --enable="rhel-sap-hana-for-rhel-7-server-rpms" \
         --enable="rhel-7-server-extras-rpms"

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         Note

         There are no e4s or eus repositories available for RHEL 7.9 and RHEL 8.10. Those are only required and available for RHEL minor versions prior to the final RHEL minor version. For more information, refer to this section in the Red Hat Enterprise Linux Life Cycle web page.

      3. Remove all files cached by yum/dnf:

         # rm -rf /var/cache/yum

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      4. Make sure no RHEL release lock is set:

         # subscription-manager release --unset

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         Release preference has been unset.

         Note

         A release lock instructs yum to access packages from e4s or eus repositories, which fails on RHEL 7.9 because there are no such repositories on RHEL 7.9.

   2. Preparing PAYG cloud instances on AWS

      1. Install the leapp-rhui-aws-sap-e4s package:

         # yum install leapp-rhui-aws-sap-e4s

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      2. Enable the rhel-7-server-rhui-extras-rpms repository:

         # yum-config-manager --enable rhel-7-server-rhui-extras-rpms

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   3. Preparing PAYG cloud instances on Google Cloud

      1. Download and install the leapp-rhui-google-v1-rhel7-sap package, as instructed in Leapp RHUI packages for Google Cloud Platform (GCP).

      2. Enable the rhui-rhel-7-server-rhui-extras-rpms repository:

         # yum-config-manager --enable rhui-rhel-7-server-rhui-extras-rpms

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   4. Preparing PAYG cloud instances on Microsoft Azure

      1. Install the leapp-rhui-azure-sap package:

         # yum install leapp-rhui-azure-sap

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      2. Enable the rhui-rhel-7-server-rhui-extras-rpms repository:

         # yum-config-manager --enable rhui-rhel-7-server-rhui-extras-rpms

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2. Completing the non-system-specific setup

   After completing the above steps, perform the remaining steps on all systems, no matter if your system is a non-cloud, BYOS cloud, or PAYG cloud system on AWS, Google Cloud, or Microsoft Azure.

   1. Stop the SAP HANA system(s) and stop all SAP processes.

      Important

      Do not unmount the SAP HANA file systems, as these are required for detecting if SAP HANA is installed and the version of the installed system.

   2. If your system is configured to start SAP processes automatically at boot time, disable the automatic start of SAP processes.
      

   3. Configure RHEL settings for SAP HANA:

      1. The SAP HANA installer in SAP HANA 2.0 SPS05 configures kernel settings in file /etc/sysctl.conf. Leave these settings in place.
      2. Additional settings recommended for SAP HANA as per SAP notes 2382421 and 2292690 are configured using the sap.conf and sap_hana.conf files in the /etc/sysctl.d directory. Settings in sap_hana.conf are valid for both RHEL 7 and RHEL 8, whereas the value for kernel.sem in sap.conf on RHEL 7 is lower than the default value on RHEL 8. Because of this, remove the line that sets kernel.sem to 1250 256000 100 1024 from /etc/sysctl.d/sap.conf. The value for vm.max_map_count is again valid for both RHEL 7 and RHEL 8, so leave this setting in place.

   4. Update your RHEL 7.9 system to the latest RHEL 7 package levels:

      # yum update

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   5. Reboot the system:

      # reboot

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   6. After the system is up and running, check and confirm that no SAP HANA systems and no SAP processes are running on the system.
      
   7. Make sure the SAP HANA file systems are available.
      

   8. Install the leapp utility:

      # yum install leapp-upgrade

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   9. Ensure there is no configuration management system (such as Salt, Chef, Puppet, Ansible) enabled or configured to attempt to restore the original RHEL 7 system.
      
   10. Ensure your system does not use any Network Interface Card (NIC) with a name based on the prefix 'eth'.
       
   11. Make sure that you have a full backup or a virtual machine snapshot of your system.
       
   12. If not done already, perform a restore test of the backup to another system, to make sure that the backup can be used for a successful restore. A restore test is also useful for getting used to the required restore activities so that you can get a working system back as quickly as possible, if necessary.

Procedure

1. Perform the pre-upgrade assessment:

   • On a non-cloud or BYOS cloud system, run:

     # leapp preupgrade --target 8.10

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   • On a PAYG cloud instance on AWS, Google Cloud, or Microsoft Azure, run:

     # leapp preupgrade --no-rhsm --target 8.10

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1. In many cases, the following inhibitors are reported:

   • Inhibitor: Detected loaded kernel drivers that have been removed in RHEL 8. Upgrade cannot proceed.
   • Inhibitor: Possible problems with remote login using a root account.

   • Inhibitor: Missing required answers in the answer file.

     The report in file /var/log/leapp/leapp-report.txt contains all necessary information, including remediation steps, to resolve these inhibitors.

2. In the case of non-cloud or BYOS cloud systems, if the message Unable to use yum successfully is reported in step target_userspace_creator and the preupgrade is aborted, this typically indicates that not all required RHEL 7 and RHEL 8 repositories are available with your activation key. To solve this problem, configure your activation key to enable all required repos as per step 1.1.a.i or re-register your system to use an activation key that has all required repositories enabled.
3. Manually resolve all the reported problems before proceeding with the in-place upgrade. As mentioned before, you can repeat this step as often as necessary until no more inhibitors are reported.

Procedure

1. Before performing the upgrade, back up all of your data to avoid potential data loss if you have not already done so.
   
2. Perform a restore test to verify that the last backup was successful.
   
3. Check and confirm again that no SAP HANA system and no SAP processes are running on the system.
   
4. Check and confirm that your SAP HANA system are not be started automatically at boot time. For more information, refer to SAP note 2315907 - Starting HANA automatically after Host has been started.
   
5. Check and confirm that the SAP HANA file systems are mounted, as a certain file located below this path is used by Leapp to detect whether the upgraded system is running SAP HANA or not, to assert related inhibitors.
   

6. Run the upgrade process:

   • On a non-cloud or BYOS cloud system, enter:

     # leapp upgrade --target 8.10

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   • On a PAYG cloud instance on AWS, Google Cloud, or Microsoft Azure, enter:

     # leapp upgrade --no-rhsm --target 8.10

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     Note

     Do not use the --channel e4s option if you upgrade to RHEL 8.10, as it is the final minor release of RHEL 8, it is not E4S release, and its support cycle differs. For more information, see the Red Hat Enterprise Linux Life Cycle Customer Portal article.

7. After the system completes the previous command, it displays a message that asks you to reboot the system. Restart the system so that it can finish the upgrade:

   # reboot

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8. The system boots into a RHEL 8-based initial RAM disk image (initramfs), upgrades all packages, and reboots again. This might take some time. Once all packages have been upgraded, the system automatically starts the RHEL 8 system.

Procedure

1. Verify that the current OS version is Red Hat Enterprise Linux 8:

   # cat /etc/redhat-release
   Red Hat Enterprise Linux release 8.10 (Ootpa)

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2. Check the OS kernel version. Note that `.el8 is essential. For example, for RHEL 8.10, it is 4.18.0-553.34.1.el8 or later:

   # uname -r
   4.18.0-553.34.1.el8

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   The Red Hat Enterprise Linux Release Dates Knowledgebase article helps you match the kernel version with a particular RHEL release.

3. Make sure no RHEL release lock is set.

   Note

   A release lock instructs yum to access packages from e4s or eus repositories, which fails on RHEL 8.10 because there are no such repositories on RHEL 8.10.

   • On a non-cloud or BYOS cloud system, run:

     # subscription-manager release --unset

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     Release preference has been unset.

   • On a PAYG cloud instance on AWS, Google Cloud, or Azure remove a file if it exists:

     # cat /etc/yum/vars/releasever
     <target_os_version>
     # rm /etc/yum/vars/releasever

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4. Verify that the system has all necessary repositories enabled:

   # yum repolist

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   • On a non-cloud or BYOS cloud system, the output should contain:

     rhel-8-for-x86_64-appstream-rpms
     rhel-8-for-x86_64-baseos-rpms
     rhel-8-for-x86_64-sap-netweaver-rpms
     rhel-8-for-x86_64-sap-solutions-rpms

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   • On a PAYG cloud instance on AWS, the output should contain:

     rhel-8-for-x86_64-appstream-rhui-rpms
     rhel-8-for-x86_64-baseos-rhui-rpms
     rhel-8-for-x86_64-highavailability-rhui-rpms
     rhel-8-for-x86_64-sap-netweaver-rhui-rpms
     rhel-8-for-x86_64-sap-solutions-rhui-rpms

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   • On a PAYG cloud instance on Google Cloud, the output should contain:

     rhui-rhel-8-for-x86_64-appstream-rhui-rpms
     rhui-rhel-8-for-x86_64-baseos-rhui-rpms
     rhui-rhel-8-for-x86_64-highavailability-rhui-rpms
     rhui-rhel-8-for-x86_64-sap-netweaver-rhui-rpms
     rhui-rhel-8-for-x86_64-sap-solutions-rhui-rpms

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     Note

     Google Cloud RHEL 7 images have the EPEL repository included. RHEL 8 images do not. Therefore, after the upgrade, you can see an error message as follows:

     $ yum repolist
     Invalid configuration value: failovermethod=priority in /etc/yum.repos.d/epel.repo; Configuration: OptionBinding with id "failovermethod" does not exist

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     In this case, remove the EPEL repo(s):

     $ rm -f /etc/yum.repos.d/epel*.repo

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   • On a PAYG cloud instance on Microsoft Azure, the output should contain:

     rhel-8-for-x86_64-appstream-rhui-rpms
     rhel-8-for-x86_64-baseos-rhui-rpms
     rhel-8-for-x86_64-highavailability-rhui-rpms
     rhel-8-for-x86_64-sap-netweaver-rhui-rpms
     rhel-8-for-x86_64-sap-solutions-rhui-rpms

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     Note

     On Cloud Providers, the repolist may contain other non-Red Hat repositories, for example, custom repositories for RHUI configuration.

5. Verify that network services are operational. For example, try to connect to the system by using the ssh command.

Procedure

1. If you have configured your RHEL 7.9 system for SAP HANA using the RHEL System Roles for SAP (the rhel-system-roles-sap package, the sap_general_preconfigure and sap_hana_preconfigure roles) and if you have not made any additional modifications to your system configuration afterwards, you can configure your system with the RHEL System Roles for SAP again.

   Note

   To verify that your system is configured according to the applicable SAP notes, you can run RHEL system roles sap_general_preconfigure and sap_hana_preconfigure in assert mode.

2. If you want to configure your system manually, the following steps are required:

   1. SAP note 2772999: Install package group server:

      # dnf group install server

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   2. SAP note 2772999: Install package libibverbs:

      # dnf install libibverbs

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   3. SAP note 2777782: Disable service abrt-ccpp:

      # systemctl disable abrt-ccpp --now

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      Note

      SAP note 2772999 version 17 and SAP note 2777782 version 23 recommend setting kernel.pid_max in the /etc/sysctl.d/sap.conf file to 4194304. As the default for this kernel parameter in RHEL 8.2 and later is already 4194304, there is no need to set this kernel parameter again.

      After modifying your system configuration as described, reboot your system.

1. At the end of the Preparing a RHEL 7 system for the upgrade procedure, remove the line containing kernel.sem from the /etc/sysctl.d/sap.conf file.

2. At the end of the 6. Verifying the post-upgrade state of the RHEL 8 system procedure, verify that the value of kernel.pid_max is 4194304 according to SAP note 2772999:

   # sysctl kernel.pid_max

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   If this is not the case, add the following line to file /etc/sysctl.d/sap.conf:

   kernel.pid_max = 4194304

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   Save the changes, and reload the file:

   # sysctl -p /etc/sysctl.d/sap.conf

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   You can run the sap_general_preconfigure and sap_netweaver_preconfigure roles in assert mode to verify if your system is compliant with the SAP notes requirements. These roles are part of the RHEL package RHEL System Roles for SAP or the Ansible collection redhat.sap_install.