Re: [linux-lvm] Can't work normally after attaching disk volumes originally in a VG on another machine

["Gang He" <ghe@suse.com>]

Hi Xen,


>>> 
> Gang He schreef op 23-03-2018 9:30:
> 
>> 6) attach disk2 to VM2(tb0307-nd2), the vg on VM2 looks abnormal.
>> tb0307-nd2:~ # pvs
>>   WARNING: Device for PV JJOL4H-kc0j-jyTD-LDwl-71FZ-dHKM-YoFtNV not
>> found or rejected by a filter.
>>   PV         VG  Fmt  Attr PSize  PFree
>>   /dev/vdc   vg2 lvm2 a--  20.00g 20.00g
>>   /dev/vdd   vg1 lvm2 a--  20.00g 20.00g
>>   [unknown]  vg1 lvm2 a-m  20.00g 20.00g
> 
> This is normal because /dev/vdd contains metadata for vg1 which includes 
> now missing disk /dev/vdc      .... as the PV is no longer the same.
> 
> 
> 
> 
>> tb0307-nd2:~ # vgs
>>   WARNING: Device for PV JJOL4H-kc0j-jyTD-LDwl-71FZ-dHKM-YoFtNV not
>> found or rejected by a filter.
>>   VG  #PV #LV #SN Attr   VSize  VFree
>>   vg1   2   0   0 wz-pn- 39.99g 39.99g
>>   vg2   1   0   0 wz--n- 20.00g 20.00g
> 
> This is normal because you haven't removed /dev/vdc from vg1 on 
> /dev/vdd, since it was detached while you operated on its vg.
> 
> 
>> 7) reboot VM2, the result looks worse (vdc disk belongs to two vg).
>> tb0307-nd2:/mnt/shared # pvs
>>   PV         VG  Fmt  Attr PSize  PFree
>>   /dev/vdc   vg1 lvm2 a--  20.00g     0
>>   /dev/vdc   vg2 lvm2 a--  20.00g 10.00g
>>   /dev/vdd   vg1 lvm2 a--  20.00g  9.99g
> 
> When you removed vdd when it was not attached, the VG1 metadata on vdd 
> was not altered. The metadata resides on both disks, so you had 
> inconsistent metadata between both disks because you operated on the 
> shared volume group while one device was missing.
> 
> You also did not recreate PV on /dev/vdc so it has the same UUID as when 
> it was part of VG1, this is why VG1 when VDD is booted will still try to 
> include /dev/vdc because it was never removed from the volume group on 
> VDD.
> 
> So the state of affairs is:
> 
> /dev/vdc contains volume group info for VG2 and includes only /dev/vdc
> 
> /dev/vdd contains volume group info for VG1, and includes both /dev/vdc 
> and /dev/vdd by UUID for its PV, however, it is a bug that it should 
> include /dev/vdc even though the VG UUID is now different (and the name 
> as well).
It looks like each PV includes a copy meta data for VG, but if some PV has changed (e.g. removed, or moved to another VG),
the remained PV should have a method to check the integrity when each startup (activated?), to avoid such inconsistent problem automatically.

Thanks
Gang 

> 
> Regardless, from vdd's perspective /dev/vdc is still part of VG1.
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com 
> https://www.redhat.com/mailman/listinfo/linux-lvm 
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/