Linux
http://www.centos.org/docs/5/html/Deployment_Guide-en-US/
Linux Documentation Project:
http://www.tldp.org/
DRBD Links
http://linux-ha.org/
http://www.howtoforge.com/drbd-on-centos-4.5
http://wiki.centos.org/HowTos/Ha-Drbd
http://www.linuxjournal.com/article/9074
http://www.nabble.com/Kernel-Panic-using-LVM2-over-DRBD-8.0.6-td14124742.html
Linux Home networking
http://www.linuxhomenetworking.com/
http://www.yolinux.com/TUTORIALS/
http://wiki.centos.org/Repositories
Fedora packages for REDHAT
http://fedoraproject.org/wiki/EPEL
Run the following command to enable EPEl repos
rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-2.noarch.rpm
Using OpenLDAP for User Authentication
http://linsec.ca/usermgmt/openldap.php