[CentOS-virt] Need to unmount an LV from host system

Tue Mar 5 20:24:13 UTC 2013
jboyce at meridianenv.com <jboyce at meridianenv.com>

Greetings -

Ok, I made a mistake that I need to fix.  Fortunately it is not a
destructive mistake, but I need some advice on how to correct the problem.

CentOS 6.3 host system named Earth

I was creating some new logical volumes within my exiting volume group for
a new virtual machine using the LVM GUI.  When I created the LV that I
plan to use for root partition of the new VM (Bacteria) I mistakenly
clicked on the box to mount the LV, and specified the mount point as /.

[root at earth ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_mei-lv_earthroot
                      5.0G  3.9G  880M  82% /
tmpfs                 5.9G  276K  5.9G   1% /dev/shm
/dev/sda1             485M  116M  344M  26% /boot
/dev/mapper/vg_mei-lv_earthvar
                      3.0G  748M  2.1G  27% /var
/dev/mapper/vg_mei-lv_bacteriaroot
                      5.0G  3.9G  880M  82% /

I tried to unmount the device, but as shown below, it is busy.

[root at earth ~]# umount /dev/mapper/vg_mei-lv_bacteriaroot
umount: /: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

I tried to force unmount the device, but that failed also.

[root at earth ~]# umount -f /dev/mapper/vg_mei-lv_bacteriaroot
umount2: Device or resource busy
umount: /: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))
umount2: Device or resource busy


What other options are there.  Is there are way to get this unmounted
without having to shutdown my host system and boot into rescue mode.  I
don't really want to shutdown my active VM's while other staff are working
on them right now.

Please cc me directly as I only receive the daily digest.  Thanks.

Jeff
Meridian Environmental