[linux-lvm] lvm partition on lv

[Randall Smith <randall@tnr.cc>]

Warning:  This may be insane.

I like the flexibility of LVM and try to use it wherever it's feasible. 
  In this case, I'd like a Xen guest OS to have control over it's LV's. 
  The method I usually see for using LVM with Xen is to create an LV and 
a filesystem on it.  I would like to instead create an LV and partition 
it with an LVM partition and maybe other partition types.  Just to test 
this I did the following:

1. lvcreate -L 100M -name test vg1
2. cfdisk /dev/vg1/test
3. create LVM partition on entire device
4. pvcreate /dev/vg1/test
5. vgcreate vg2 /dev/vg1/test
6. vgchange -ay /dev/vg2
7. lvcreate -L 50M -n testlv vg2
8. mkfs.ext3 /dev/vg2/testlv
9. mkdir /mnt/test
10. mount /dev/vg2/testlv /mnt/test

And it worked!  Cool!

Let's say on /dev/vg1/test I had one LVM partition and one ext3 
partition.  How can I access those separate partitions since it's only 
one device (/dev/vg1/test)?  Normally, a partitioned block device 
(/dev/hda) would show up like /dev/hda1, dev/hda2, etc.

In the example above, I'm partitioning the LV and using the partition on 
the same system, which is useless.  What I will be doing is giving the 
disk image /dev/vg1/test to a Xen guest so it can have it's own VG and 
LVs.  Are there potential problems I should look out for and/or tweaking 
I should do to make this work optimally?

Randall