How to check Upgrade Fails and Data in Partition is Lost when BTRFS is Mounted or Loaded

[#1]

Article Number

000003154

Applies To

RSA Product Set: NetWitness Platform
RSA Product/Service Type: All Nodes
RSA Version/Condition: 12.3.x ,12.4 or later
Platform: Alma & CentOS
 

Issue

 Since Alma OS does not support btrfs , this is no longer supported and may result in data loss if you are using the btrfs file system.
(Netwitness by default doesn't use btrfs file system). If it is being used by a NW customer, it is required to unmount the btrfs partition and relocate the data present in it before upgrading to ALMA OS.

Scenario 1
Customer gets a reference to check this KB article when they run the nw-precheck-tool with os-migration-checklist parameter.

Scenario 2
If precheck tool is not run and BTRFS file system is mounted, Upgrade fails with Leapp Preupgrade failure. You will see below error in /var/log/salt/minion logs and /var/log/leapp/leapp-report.txt
Leapp treats btrfs as an inhibitor and halts the upgrade.

/var/log/salt/minion

[salt.loaded.ext.module.nw_platform:523 ][INFO    ][15475] [4/5] Running leapp pre-upgrade
[salt.loaded.ext.module.nw_platform:556 ][ERROR   ][15475] Failed to execute "leapp preupgrade"

/var/log/leapp/leapp-report.txt

Risk Factor: high (inhibitor)
Title: Btrfs has been removed from RHEL8
Summary: The Btrfs file system was introduced as Technology Preview with the initial release of Red Hat Enterprise Linux 6 and Red Hat Enterprise Linux 7. As of versions 6.6 and 7.4 this technology has been deprecated and removed in RHEL8.

Remediation: [hint] In order to unload the module from the running system, check the accompanied command.
[command] modprobe -r btrfs


 

Cause

BTRFS partition is not supported in ALMA. During OS migration, if BTRFS is mounted, then the upgrade fails and  if the data present in the partition will be lost and will no longer be available via NW after upgrade.
 

Resolution

Case 1: BTRFS is Mounted

1. Execute the following command to check if BTRFS is mounted.

   mount | grep btrf

            Image description
 

2. Follow these steps to unmount the BTRFS partition.

1. Relocate the data.
2. Unmount the BTRFS partition using the following command

   umount -l <btrfs partition path>

3. You can get the btrfs partition info from /etc/fstab or df -hT commands
4. Remove the BTRFS partition from /etc/fstab
5. Verify if the kernel is still unloaded using lsmod | grep btrfs.
6. If the kernel is still loaded, use below command to  unload the btrfs kernel module

   modprobe -r btrfs

7. Trigger / Retrigger the Upgrade

Case2: BTRFS is Loaded, not Mounted

1. Execute the following command to check if BTRFS is mounted.

   lsmod | grep btrfs

 
             Image description

2. Execute the following command to unload the BTRFS.

   modprobe -r btrfs

   Note: Before unloading BTRFS, ensure that the BTRFS partition is unmounted.