Hi all,

Does anyone have a working example of creation of a logical storage pool and volume?

I'm hitting a wall getting logical volumes to work on RHEL 6 beta.

There's a single drive I'm trying to setup (sdc) as a libvirt managed logical storage pool, but all volume creation on it fails.

Here's what I'm finding so far:

  Prior to any storage pool work, only the host boot drive (sda) is in lvm.

  # vgs
    VG       #PV #LV #SN Attr   VSize   VFree
    vg_host2   1   3   0 wz--n- 465.27g    0
  # pvs
    PV         VG       Fmt  Attr PSize   PFree
    /dev/sda2  vg_host2 lvm2 a-   465.27g    0
  # ls -la /dev/mapper
  total 0
  drwxr-xr-x.  2 root root    120 Jun  1 03:12 .
  drwxrwxrwt. 21 root root   3920 Jun  1 03:12 ..
  crw-rw----.  1 root root 10, 58 May 31 14:08 control
  lrwxrwxrwx.  1 root root      7 May 31 14:10 vg_host2-lv_home -> ../dm-7
  lrwxrwxrwx.  1 root root      7 May 31 14:08 vg_host2-lv_root -> ../dm-0
  lrwxrwxrwx.  1 root root      7 May 31 14:10 vg_host2-lv_swap -> ../dm-8
  #


  Creation of a logical storage pool, using sdc:

# virsh pool-define-as guest_images_lvm logical - - /dev/sdc libvirt_lvm /dev/mapper
  Pool guest_images_lvm defined

  # virsh pool-info guest_images_lvm
  Name:           guest_images_lvm
  UUID:           17398035-8000-7252-ab25-58db95aed130
  State:          inactive

  # virsh pool-build guest_images_lvm
  Pool guest_images_lvm built

  #


  The physical device and volume group are seen in lvm:

  # pvs
    PV         VG          Fmt  Attr PSize   PFree
    /dev/sda2  vg_host2    lvm2 a-   465.27g      0
    /dev/sdc   libvirt_lvm lvm2 a-   465.76g 465.76g
  # vgs
    VG          #PV #LV #SN Attr   VSize   VFree
    libvirt_lvm   1   0   0 wz--n- 465.76g 465.76g
    vg_host2      1   3   0 wz--n- 465.27g      0
  #


  Starting the logical pool works:

  # virsh pool-start guest_images_lvm
  Pool guest_images_lvm started

  #


  Creation of volumes fail:

  # virsh vol-create-as guest_images_lvm volume1 8G
  error: Failed to create vol volume1
error: internal error '/sbin/lvcreate --name volume1 -L 8388608K /dev/mapper' exited with non-zero status 3 and signal 0: Volume group name expected (no slash)
  Run `lvcreate --help' for more information.

  #

So, it looked like "/dev/mapper" in the pool-define-as command should have instead been the LVM volume group again. That doesn't work either though:

# virsh pool-define-as guest_images_lvm logical - - /dev/sdc libvirt_lvm libvirt_lvm
  Pool guest_images_lvm defined

  # virsh pool-build guest_images_lvm
  Pool guest_images_lvm built

  # virsh pool-start guest_images_lvm
  Pool guest_images_lvm started

  # virsh vol-create-as guest_images_lvm volume1 8G
  error: Failed to create vol volume1
  error: cannot read path 'libvirt_lvm/volume1': No such file or directory

Looking in the libvirtd logs for this last attempt, the volume was actually successfully created. But libvirtd then checks for it's presence (wrongly!), doesn't find it, and then lvremove's it:

03:01:24.000: debug : virRunWithHook:832 : /sbin/lvcreate --name volume1 -L 8388608K libvirt_lvm
  ...
03:01:24.223: debug : virRunWithHook:848 : Command stdout: Logical volume "volume1" created
  ...
03:01:24.223: error : virStorageBackendLogicalCreateVol:616 : cannot read path 'libvirt_lvm/volume1': No such file or directory
  ...
03:01:24.223: debug : virRunWithHook:832 : /sbin/lvremove -f libvirt_lvm/volume1


Guessing I'm either doing something wrong, or hitting bugs, or ?

Anyone have ideas/suggestions/etc?

Regards and best wishes,

Justin Clift

--
Salasaga  -  Open Source eLearning IDE
              http://www.salasaga.org

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