RE: [linux-lvm] Red Hat Advanced Server + LVM

["Sharad Tiwari" <sharad tiwari wipro com>]

hi all,

         While testing the LVM2 I came across this scenario.

If I have created a volume group(say 'testvg') containg two physical volumes say /dev/sda5 and /dev/sda6, and then remove one of the physical volume say /dev/sda6 and then do a pvdisplay it shows /dev/sda6 as an unknown device ... 

Also on doing a vgdisplay the volume group testvg I get the following on stdout ...

[root earth root]# vgdisplay
Entering CP VMS CP_VMS_vgdisplay function
  Couldn't find device with uuid 'U5Jw21-3AWD-F7t3-a7CI-cpd1-EVAZ-u3LtgX'.
  Couldn't find all physical volumes for volume group testvg.
  Volume group "testvg" doesn't exist
[root earth root]#

Now doing a vgreduce gives the proper result. So I did not understand why we are prividing this feature (using pvremove) of removing a physical volume from  an existing VG.


The following is the sequence of commands issued.( after creating the PVs and VGs) ...


[root xyz root]# pvdisplay
Entering CP VMS CP_VMS_pvdisplay function
  --- Physical volume ---
  PV Name               /dev/sda8
  VG Name               testvg
  PV Size               496.00 MB / not usable 0
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              124
  Free PE               49
  Allocated PE          75
  PV UUID               0m0xxl-xRK3-ojHc-TU8x-BgSF-sy6C-2vKquU

  --- Physical volume ---
  PV Name               /dev/sda7
  VG Name               testvg
  PV Size               396.00 MB / not usable 0
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              99
  Free PE               99
  Allocated PE          0
  PV UUID               U5Jw21-3AWD-F7t3-a7CI-cpd1-EVAZ-u3LtgX

[root xyz root]# pvremove -ff /dev/sda7
Entering CP VMS CP_VMS_pvremove function
Really WIPE LABELS from physical volume "/dev/sda7" of volume group "testvg" [y/n]? y
  WARNING: Wiping physical volume label from /dev/sda7 of volume group "testvg"
  Labels on physical volume "/dev/sda7" successfully wiped
[root earth root]# pvdisplay
Entering CP VMS CP_VMS_pvdisplay function
  Couldn't find device with uuid 'U5Jw21-3AWD-F7t3-a7CI-cpd1-EVAZ-u3LtgX'.
  --- Physical volume ---
  PV Name               /dev/sda8
  VG Name               testvg
  PV Size               496.00 MB / not usable 0
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              124
  Free PE               49
  Allocated PE          75
  PV UUID               0m0xxl-xRK3-ojHc-TU8x-BgSF-sy6C-2vKquU

  --- Physical volume ---
  PV Name               unknown device
  VG Name               testvg
  PV Size               396.00 MB / not usable 0
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              99
  Free PE               99
  Allocated PE          0
  PV UUID               U5Jw21-3AWD-F7t3-a7CI-cpd1-EVAZ-u3LtgX


The other question is ... if I have a VG spanning across two PVs and then create an LV ( big enough to span across two disks ... ) and then do a vgreduce to remove one of the PV, it allows me to do that but does not change the size of the LV or VG being printed ...

Are these known bugs and what is the work around ?

Thanks for the help.

Sharad.

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