Create a new Linux partition, ie. Partition type 83 on your newly installed disk, in this case hdb:
Now create a new LVM member with the new partition:
Extend the volume group to include your new partition (my volume group is called vg_data, you can find out what yours is by doing a 'vgscan')
vgextend vg_data /dev/hdb1
List the details about your volume group:
Do some maths, towards the end of the display you will see something like:
...snip... Total PE / Free PE X / 0 ...snip... Total PE / Free PE Y / Y ...snip...
So now you have to add X and Y which will give you the total amount to extend your logical volume by.. When you extend it, you say *what* you want to extend it too, rather than how much.
So. In my cas X+Y was 99682, so I do (my logical volume is called lv_data):
lvextend -l 21629 /dev/vg_data/lv_data
Ok, so it should be allocated now, if you do a 'vgdisplay --verbose' you should see there are no free PE's anymore..
Find out where your mount point is for your logical volume (in my case lv_data), mines /data and run:
Thats it, 'df -h' to see your results!