Configure FalconStor (CentOS 8) for Booting Single to Dual VIOS Setup

This process helps to identify and configure FalconStor to work on both Single and Dual VIOS. This process requires Internet access.

Check configuration:

1. Log in to your FalconStor StoreSafe System as root.
2. Check for the multipath library and service status.
   • Run the below command to check the multipath library status
     ldd /usr/sbin/multipath | grep -i "not found\|failed"
Sample Output:
     
     
   • 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 Output:
   
   
   
4. Run the following command to determine if multipath is enabled
   multipath -ll
Sample Output:
5. If you find libraries missing and the multipath service in a failed state when performing the above checks proceed to the next section.
   
   

Installing Missing Libraries:

1. Run yum update -y installing missing libraries
   
   If the installation failed because the URL in the repository was no longer available then the repository URL needs to be updated. Use the following commands to update the repository URL so that yum can install the required missing libraries
   
   Execute the below commands one by one to update the repository URL
   

   cd /etc/yum.repos.d/
   

   sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
   

   sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*

   
   Please rerun the yum update -y again.
   
   
2. Now install the missing library package for multipathing using the below command
   yum install liburcu*
   Sample output:
   

Verification:

1. Once the missing package is installed, verify for any other missing packages.
   
   Check the multipath library status using below command
   ldd /usr/sbin/multipath | grep -i "not found\|failed"

   If this command returns empty then all required packages are installed if not, please contact Skytap Support for further assistance.

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 returned 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
   

Updating inc_hba.conf:

1. Perform the following command to check if you have an entry that has SCSI entry on it. 

   cat /usr/local/vtl/etc/inc_hba.conf

   Sample output:
   
   
   
2. If it doesn't have an SCSI entry, then perform the below command to add an entry.
   

   echo "IBM POWER Virtual SCSI Adapter 1.5.9" >> /usr/local/vtl/etc/inc_hba.conf

Finding OS Disk WWID:

1. To identify the OS Disk Device, run the below command
   
   df -h /

   This shows which device is mounted at /. It might list something like /dev/sda1 or /dev/mapper/cl-root. Note down the Filesystem information.

   Sample output:
   

    

2. Examine the Block Device Tree by running the below command and compare them with which tree they are from, using the information we noted in the previous step.
   lsblk
   Sample output:
   
   
   In this case, we can see /dev/mapper/cl-root is mapped to sda.
   
   
3. With information from the previous step, please run the below command string to get the WWID of the OS disk.
   

   read -p "Enter device name (e.g. sda, sdb): " DEV; WWID=$(/lib/udev/scsi_id --whitelisted --replace-whitespace --device=/dev/$DEV); echo "WWID of $DEV: $WWID"

   When you run this command string, specify the device name. and press enter. In this example its sda and note down its WWID number as we need that info for the next segment.
   Sample output:
   
   
   

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 {
wwid ".*"
}
blacklist_exceptions {
wwid "<Your OS Disk WWID Number>"
}

Note: On this text block, modify the value "<Your OS Disk WWID Number>"  with your OS WWID disk that was noted from the segment "Finding OS Disk WWID" step 3.

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

Now your VM should be configured for the multipathing and can seamlessly transition from Single VIOS to Dual VIOS and this is a one-time configuration. If you encounter any issues in this procedure please reach out to Skytap Support support@skytap.com for further assistance.