[CentOS] CentOS6.6 installation failure

Mon Apr 20 12:21:12 UTC 2015
lhecking at users.sourceforge.net <lhecking at users.sourceforge.net>

I have been installing CentOS for years using PXE, kickstart and NFS, but the
procedure fails with CentOS 6.6 for some reason.

A PXE-initiated, manual install goes through all the setup steps, and once
rpm installation has started, it dies after a few packages:

anaconda 13.21.229 exception report
Traceback (most recent call first):
  File "/usr/lib/anaconda/yuminstall.py", line 1006, in _handleFailure
    os.unlink(package.localPkg())
  File "/usr/lib/anaconda/yuminstall.py", line 196, in callback
    self.ayum._handleFailure(po, trynumber)
OSError: [Errno 30] Read-only file system: '/mnt/source/Packages/mailcap-2.1.31-2.el6.noarch.rpm'

When a kickstart file is used instead, the installation dies at a different
package.

I have tried providing the OS installation files from different machines,
checked package integrity etc., but cannot figure out what is happening here.

The anaconda traceback file also has

12:19:59,354 WARNING : Failed to get file:///mnt/source/Packages/mailcap-2.1.31-
2.el6.noarch.rpm from mirror 1/1, or downloaded file is corrupt
12:19:59,354 WARNING : package download failure, retrying automatically

That said, installing 6.4 off the same NFS server works just fine.