[libvirt-users] for a guest accessing host "full disk", how to prevent host vgscan

[David Mansfield]

Hi All.

I have a dell system with a H700 raid.  Within the hardware RAID config 
I've created a "virtual disk" which I have assigned to one of my 
guests.  On the host the device is "/dev/sdb", on the guest it's "/dev/vdb".

This works fine.

Within the guest, we have created lvm PV on /dev/vdb (using the whole 
disk - no partitions) and created a volume group.  The guest's hostname 
is "argo" and the vg is called "vg_argo_bkup".

When I reboot the host, it does a vgscan and finds the volume group and 
activates it in the _host_, which I need to prevent (I think??).

I have successfully done this by filtering "/dev/sdb" in 
/etc/lvm/lvm.conf (which does NOT work as advertised BTW), but 
referencing the extremely volatile SCSI "sd*" names seems a terrible way 
to do this.  If I fiddle around in the HW raid config, the /dev/sd? may 
change.

I plan on creating about 10 more VM's spread over a number of machines 
over the next weeks with a very similar setup, and the admin overhead 
seems like it'll be onerous and error-prone.

I'd love to be able to filter the volume groups by VG name instead of pv 
device node.  The host's hostname is "narnia" and I'd love to say, 
'vgscan --include-regex "vg_narnia.*"' or something similar, if you get 
my drift.

Does anyone have a best practice for this?  I'm sure iSCSI enthusiasts 
must have the exact same issue all the time.

Oh... I'm using centos 6.2 on host and guest, 
libvirt-0.9.4-23.el6_2.1.x86_64, although it hardly seems a libvirt 
issue at all, it seems to be a lvm host issue mainly.

Thanks,
David Mansfield