I've been running into a reproducible problem when using default LVM volume group names to present block devices for virtual machines in KVM, and I'm wondering why it is happening.
On dom0 I make a default VolGroup00 for the operating system. I make a second VolGroup01 for logical volumes that will be block devices for virtual systems.
In VolGroup01, I make two lv's for one system: lv.sys1, and lv.sys1-data.
I then build a new virtual machine called sys1, using lv.sys1 for the root filesystem, and lv.sys1-data for an independent data partition. Everything works great after installation, and vgdisplay on both systems looks great.
If I then run vgscan, however, on the host system, it picks up the VolGroup01 I created _within_ the virtual machine, so I now have 2 VolGroup01's with different UUIDs showing up on dom0.
Now I can see how vgscan would mistakenly see the VolGroup01 of sys1 on the block device lv.sys1-data, but why are the VolGroup00 vg's not colliding as well?
When a pvdisplay is run, I have a new "physical volume" that is actually just a logical volume of the original VolGroup01:
[root@iain2 ~]# pvdisplay WARNING: Duplicate VG name VolGroup01: Existing FNiKc9-BB3t-ziMg-prWW-n8RA-OMzk-obiKnf (created here) takes precedence over C8fNMV-aeSW-syIn-fWJZ-vJdK-N0As-Itrvfi WARNING: Duplicate VG name VolGroup01: Existing FNiKc9-BB3t-ziMg-prWW-n8RA-OMzk-obiKnf (created here) takes precedence over C8fNMV-aeSW-syIn-fWJZ-vJdK-N0As-Itrvfi --- Physical volume --- PV Name /dev/VolGroup01/lv-sys1-data VG Name VolGroup01 PV Size 40.00 GB / not usable 4.00 MB Allocatable yes (but full) PE Size (KByte) 4096 Total PE 10239 Free PE 0 Allocated PE 10239 PV UUID FTA4QU-ydZ7-e2Yy-nBsi-t4st-3jj7-IAkQH8
--- Physical volume --- PV Name /dev/sda3 VG Name VolGroup00 PV Size 39.06 GB / not usable 29.77 MB Allocatable yes (but full) PE Size (KByte) 32768 Total PE 1249 Free PE 0 Allocated PE 1249 PV UUID tTViks-3lBM-HGzV-mnN9-zRsT-fFT0-ZsJRse
--- Physical volume --- PV Name /dev/sda2 VG Name VolGroup01 PV Size 240.31 GB / not usable 25.75 MB Allocatable yes PE Size (KByte) 32768 Total PE 7689 Free PE 5129 Allocated PE 2560 PV UUID ZE5Io3-WYIO-EfOQ-h03q-zGdF-Frpa-tm63fX
Has anyone experienced this? It's very unnerving to know your data is intact as you add new logical volumes for kvm systems. I suppose the lesson learned here is to provide VGs with specific host names.