WHY !!! do you need to install a old and UNSUPPORTED version of CentOS ??????
CentOS 6.4 is UNSUPPORTED
CentOS 6.5 is UNSUPPORTED
CentOS 6.6 is UNSUPPORTED
the current is CentOS 6.7 in the older 6 series , with CentOS 7.1 as the current version
3.9 gig is WAY TOO SMALL
i take it you did not read the system requirements
3.9 is SMALLER that the 4.3 gig install dvd
https://access.redhat.com/documentat...mmend-x86.html
normally 6 to 9 gig is the BARE MINIMUM of drive space