Creating local yum repositories using ISO files

Create repository location (any suitable location) and change directory
#mkdir -p /var/ftp/pub/yumrepo
#cd /var/ftp/pub/yumrepo

Create directory for RPM packages
#mkdir CentOS
Create mount point for ISO disks
#mkdir disk1 disk2 disk3 disk4 disk5 disk6 disk7 disk8

Mount ISO disks and loop
#mount -r -o loop  disk1
... 
#mount -r -o loop  disk8 


Copy RPM packages 
#cp disk*/CentOS/* .
#cp disk1/repodata/comps.xml   .


Install createrepo package
#rpm -Uvh CentOS/createrepo*


Create repository
#createrepo -g comps.xml   .

Configure yum to use the newly created repo. Can use command line or GUI