RHEL8では、nobarrierオプションが利用できなくなってる。
https://access.redhat.com/solutions/5315771
http://smalldatum.blogspot.com/2018/01/xfs-nobarrier-and-413-linux-kernel.html
There might be two workarounds:
switch from XFS to ext4
echo “write through” > /sys/block/$device/queue/write_cache