[KLUG Members] How do I resize a root LV?

[Adam Williams]

> I want to shrink a LV mounted as root. I have no problems resizing non-root
> LV's, but to resize the root fs and LV the root file system needs to be
> unmounted. I tried to do this in single user mode, but no dice. Root
> partition is still in use.

We are talking about ext2/3?  What your hitting is a filesystem
limitation that they can't be resized online.  If using XFS see the xfs
utilites as XFS can be resized online.

> When I boot with a BBC or Knoppix CD, the LV info on the hard disk is never
> read. The kernel loaded from the CD just sees the hard disk as having a
> small /boot partition and a bunch of unallocated type 83 sectors. How do I
> get the kernel loaded from the CD to recognize the LVM structure on the hard
> disk so I can resize the unmounted root LV?

Does it provide the vg.../lv... utilities?

You need to run "vgscan" to probe the physical devices attached to the
system for LVM data.  You can then 'activate' a volume group by doing a
"vgchange -ay"  - 'Vary On' "A"ll volume groups and assume "Y"es to all
prompts.