Red Hat provides three kernel flavors for the RHEL3 x86_64 port:
1. ia32e     ==> smp, works on both EM64T and AMD64
2. x86_64    ==> up, works only on AMD64
3. x86_64smp ==> smp, works only on AMD64

To see which arch kernel you are running, do:
# rpm -qf /boot/vmlinuz-`uname -r` --qf "%{ARCH}\n"

As always, the OCFS module needs to match the kernel flavor one
is using. Please note that there in no "up" flavor for the EM64T
kernel as these chips provide hyperthread support.