Hi, since centos/redhat runs on 3.10 kernel, orca will not install, even though it seems to indicate in the docs it should be fine.
INFO Verifying your system is compatible with Orca
FATA Your kernel version 3.10.0 is too old. Orca requires at least version 3.16.0.
I have 1.9.1 installed, so I did not follow the instructions for that part, and went straight to orca installation.