I tried a RHEL6, with 2.6.32. Fio does not work. I give up.
Please, provide a full OVA.
I tested it under
unbuntu:~$ uname -a
Linux ubuntu 5.4.0-48-generic #52-Ubuntu SMP Thu Sep 10 10:58:49 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
sperf@ubuntu:~$ cat /etc/issue
Ubuntu 20.04 LTS \n \l
Sorry for the bugs you met. I'll fix it quickly.