This is a very short post. Now, when working with glusterfs, one requires userspace-rcu package. But in certain operating systems like centos-7 and even RHEL 7, when trying to install the userspace-rcu and userspace-rcu-devel, one could see that they are greeted by the package not found error. After searching for the root cause, it seems like a certain repository is not enabled. So, the one workaround I found was to install the epel-release rpm using the command,