Configure RHEL 9.4 for Dual VIOS

This process helps to identify and configure RHEL (9.4) to migrate from Single VIOS to Dual VIOS setup. Skytap recommends creating a template of your environment prior to running the following procedure. 

Check configuration:

1. Log in to your RHEL System as root
2. Check for the multipath library and service status
   • Run following command to check the multipath library status:
     ldd /usr/sbin/multipath | grep -i "not found\|failed"
     Sample Output:
     If this command returns empty then all required packages are installed if not, please install packages using the following commands:
     yum update -y 
yum install liburcu*
   • Run the following command to check the status of the "multipathd" service
     systemctl status multipathd
     Sample Output:
3. Run the following command to check if the path is empty
   ls -l /etc/multipath/
   
   Sample expected output:
   
   
   Sample unexpected output:
   
   
4. Run the following command to determine if multipath is enabled
   multipath -ll
   
   Sample expected output:
   
   
   Sample unexpected output:

Your VM now should be configured for the multi-pathing and can seamlessly transition from Single to Dual VIOS. 

If you encounter any issues, such as empty files, Service not running and/or the absence of multipath.conf file when performing the checks mentioned above, please continue with the Updating dracut.conf section.

Updating dracut.conf:

1. We need to add the multipath module to the dracut.conf file. Run the following command to check if this entry is available:
   cat /etc/dracut.conf | grep -i 'add_dracutmodules+=" lvm multipath "'
2. If the above command returns an empty line, run the following command to add the configuration
   echo 'add_dracutmodules+=" lvm multipath "' >> /etc/dracut.conf
   
   The resulting file should look like below
   

Creating multipath configuration:

1. Execute the following commands to create the /etc/multipath.conf configuration file, load the multipath module, and set chkconfig for the multipathd to on
   mpathconf --enable
   
   
2. Edit /etc/multipath.conf file using vi or nano editor and update the file with the following entries.
   vi /etc/multipath.conf

defaults {
user_friendly_names yes
find_multipaths yes
}
devices {
device {
         vendor "AIX"
         product "VDASD"
         path_grouping_policy "multibus"
         path_checker "directio"
         features "0"
         hardware_handler "0"
         prio "const"
         failback immediate
         rr_weight "uniform"
         no_path_retry 60
     }
}
blacklist {
}

Rebuilding initramfs

1. Rebuild the initramfs with the following command
   dracut -f -v

Rebooting the LPAR

1. Post rebuild the initramfs, reboot the LPAR using the below command
   shutdown -Fr now

If you continue to encounter any issues in this procedure please reach out to Skytap Support support@skytap.com for further assistance.