Procedure to deactivate vg00 during an active login without the "in use" error.
 

In HP-UX you can boot the system into LVM Maintenance mode
in order to perform lvm maintenance on vg00. I am seeking an
equivalent process via Redhat Linux Enterprise Servers, so I
would appreciate it very much if someone can post the exact
procedure to accomplish this function.
Thank You!!!

The exact maintenance that I am trying to perform is to restore
the PVID on the PV associated with VG00.
/sbin/pvscan
PV /dev/hda2 VG vg00 lvm2 [37.19 GB / 22.62 GB free]
Total: 1 [37.19 GB] / in use: 1 [37.19 GB] / in no VG: 0 [0 ]

When I try to execute the "pvcreate" command to restore the PVID
on /dev/hda2 I get the following results.

Really INITIALIZE physical volume "/dev/hda2" of volume group "vg00" [y/n]? y
Can't open /dev/hda2 exclusively. Mounted filesystem?

This is a "catch-22" since I would have to "umount" all filesystems
associated with vg00 which includes "/usr" where the actual "pvcreate"
command resides and "/etc under /" where the "vg00_00000.vg" config
file exists. So the question is still basically the same as I am
looking for the actual proceedure to accomplish this task?

Need more info. :) What is the exact maintenance you're looking to perform on vg00 (presumably a volume group)? Most maintenance you can perform on a live system; there are exceptions, like resizing the logical volume that is mounted to /.

# umount -l /dev/vg00/lvm2

Proceed with your PV commands.

Then proceed with what you're doing - please note, if you're trying to bring down / up a VG that you're actively using - that's not recommended. In most cases dealing with a live environment can be a pain - you may need to schedule a downtime in order to boot your system into runlevel 1; or temporarily use a rescue environment.