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I'm experiencing a strange issue, after I extended the HP RAID array

This server acts as a hypervisor (CentOS - KVM) and I'm using logical volumes for the KVM guests. When I check the physical volumes (pvs) on the hypervisor - for some reason it shows the physical volumes from the KVM guests as well (the same applies to volume groups and logical volumes)

# pvs
  PV                                            VG      Fmt  Attr PSize   PFree  
  /dev/disk/by-id/dm-name-vg_01-vm01       vg_vm01   lvm2 a--   49.51g   4.88g
  /dev/disk/by-id/dm-name-vg_01-vm02     vg_vm02  lvm2 a--  159.51g   4.88g
  /dev/disk/by-id/dm-name-vg_01-vm03       vg_vm03  lvm2 a--  159.51g   4.88g
  /dev/disk/by-id/dm-name-vg_01-vm04      vg_vm04  lvm2 a--   49.51g      0 
  /dev/disk/by-id/dm-name-vg_01-vm05       vg_vm05  lvm2 a--  159.51g   4.88g
  /dev/disk/by-id/dm-name-vg_01-vm06       vg_vm06  lvm2 a--  159.51g   4.88g
  /dev/disk/by-id/dm-name-vg_01-vm07       vg_vm07  lvm2 a--   49.51g      0 
  /dev/disk/by-id/dm-name-vg_01-vm08       vg_vm08  lvm2 a--  159.51g   4.88g
  /dev/sda2                                     vg_main lvm2 a--   24.00g      0 
  /dev/sda3                                     vg_kvm  lvm2 a--    1.61t 702.17g

I'm not sure if this is related but after I extended the HP RAID array I run partprobe on the system.

Please advise how to fix this and why this issue occurs.

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1 Answer

up vote 1 down vote accepted

This is completely normal. KVM is a type 2 hypervisor. Basically, it runs under the host OS. Actually, this information should have been there already even before you extended your storage.

This is fine.

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Thanks for reply. I must admit that I didn't formatted these logical volumes on the hypervisors. I just use RAW LVMs for guests. I don't see them on the second server. I think they appeared after I run partprobe. –  HTF Nov 27 '12 at 21:54
    
Actually KVM is a hybrid type 1 and 2 hypervisor (think 1.5). It's in parallel with the OS sharing the kernel. It's not on top of the OS like a full type 2 hypervisor. Its heart is running in kernel land and the management interface is in user land. –  steven Jun 14 at 17:48
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