The documentation to move etcd contents to another disk are wrong and/or missing steps    

4.12    

All the time

1. Have an OCP 4.12 with a second disk attached to the control-plane nodes.
2. Follow steps in documentation https://docs.openshift.com/container-platform/4.12/scalability_and_performance/recommended-performance-scale-practices/recommended-etcd-practices.html#move-etcd-different-disk_recommended-etcd-practices
    

The first MachineConfig yaml definition fails in the nodes because semanage command in sync-var-lib-etcd-to-etcd.service systemd unit fails with: "ValueError: Target /var/lib/etcd is not valid. Target is not allowed to end with '/'"

After removal of '/' in Target, the next error is: "ValueError: Substitute /sysroot/ostree/deploy/rhcos/var/lib/etcd/ is not valid. Substitute is not allowed to end with '/'"

After the removal of that other extra '/', the semanage command works, although:

a. The rsync command fails with Permission denied: "rsync: change_dir "/sysroot/ostree/deploy/rhcos/var/lib/etcd" failed: Permission denied (13)". Fixed by enabling 'rsync_full_access' selinux boolean

b. The semanage isn't passing the same selinux context to the newly created /var/lib/etcd path. Fixed by adding the file context 'container_var_lib_t' to /var/lib/etcd (semanage fcontext -a -t container_var_lib_t '/var/lib/etcd(/.*)?')

Steps in documentation should be corrected to include the 'rsync_full_access' SELinux boolean and also correct the semanage command to properly set file context in /var/lib/etcd path.