If you need to install the OS in an offline environment, then you can use the ISO image of the DVD as a local repo in order to install additional packages. To follow these steps, I make the following assumptions:
mkdir /mnt/disc
mount /dev/sr0 /mnt/disc
cp /mnt/disc/media.repo /etc/yum.repos.d/rhel9dvd.repo
chmod 644 /etc/yum.repos.d/rhel9dvd.repo
echo "baseurl=file:///mnt/disc/AppStream" >> /etc/yum.repos.d/rhel9dvd.repo
echo "enabled=1" >> /etc/yum.repos.d/rhel9dvd.repo
yum clean all
yum update
yum install fio
Note that if you have installed OS with GUI, then the DVD may be automounted to a path like
/run/media/[username]/RHEL-9-3-0-BaseOS-x86_64in which case you will need to amend the baseurl parameter appropriately, or change the mount point
You can confirm where the disk device is by using
lsblk. Optical disk drives usually look like/dev/srXwhereXis a number
If using Redhat, it will give the following warning every time
yumis run:This system is not registered with an entitlement server. You can use subsription-manager to register. This can be ignored if using in an offline environment