From: Ignoramus28017 on
This was a lot more trouble than I thought as gparted was refusing to
create partitions bigger than 793 GiB. All kinds of tools like parted
and such were not able to create a large enough logical volume.

Finally, this sequence worked:

$ aptitude install lvm2
$ reboot

after reboot:

$ modprobe dm-mod

$ dd if=/dev/zero of=/dev/sdb bs=512 count=1 # Zero out first block to enable adding to LVM
$ pvcreate /dev/sdb # make it physical volume
$ vgcreate datavg /dev/sdb # creates volume group
$ lvcreate -n datavol -l 1251678 datavg # creates logical volume
$ ls -l /dev/datavg/datavol
lrwxrwxrwx 1 root root 26 2008-01-25 14:16 /dev/datavg/datavol -> /dev/mapper/datavg-datavol
$ mkfs -t ext3 /dev/datavg/datavol # make ext3 filesystem

/etc/fstab:
/dev/datavg/datavol /data ext3 defaults 0 0