LVM is "inactive" on first reboot after installation

[n43w79]

> What release of Debian, and what version of "lvm2" are you using?
>
My FAI server:
# cat /etc/debian_version
6.0.3
# dpkg --list | grep lvm2
ii  lvm2  2.02.66-5  The Linux Logical Volume Manager
# uname -a
Linux fai0 2.6.32-5-686 #1 SMP Thu Nov 3 04:23:54 UTC 2011 i686 GNU/Linux
# dpkg --list | grep fai
ii  fai-client  3.4.8  Fully Automatic Installation client package
ii  fai-doc  3.4.8  Documentation for FAI
ii  fai-quickstart  3.4.8  Fully Automatic Installation quickstart package
ii  fai-server  3.4.8  Fully Automatic Installation server package
ii  fai-setup-storage  3.4.8  automatically prepare storage devices

System installed by FAI:
# cat /etc/debian_version
6.0.5
# dpkg --list | grep lvm2
ii  lvm2  2.02.66-5  The Linux Logical Volume Manager
# uname -a
Linux opsi1 2.6.32-5-686 #1 SMP Sun May 6 04:01:19 UTC 2012 i686 GNU/Linux