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RE: [linux-lvm] LVM1 - "VGDA in kernel and lvmtab are NOT consistent"error following lvm operations



Errr, no.  Your config is way more sophisticated than ours.  Our LVM
problems appeared because we were using Xen virtualisation (hence the
Dom0/DomU description) and managed to get two virtual machines accessing the
same VG simultaneously.  Apart from that, LVM has worked extremely well for
us (but we are running the latest dev version of LVM2 rather than LVM1).

I think you will need the help of someone who really understands the guts of
LVM rather than a mere user such as myself :-)

> -----Original Message-----
> From: Dave [mailto:davo_muc yahoo com]
> Sent: 28 July 2006 11:26
> To: Roger Lucas; LVM general discussion and development
> Subject: Re: [linux-lvm] LVM1 - "VGDA in kernel and lvmtab are NOT
> consistent"error following lvm operations
> 
> Hi Roger,
> 
> Thanks for your reply.  I'm not sure if I'm facing the same issue, but I
> can tell you this...  I have 4 servers, 2 sets of 2 node clusters.  One
> application cluster of 2 servers, and one database cluster of servers.
> Both servers in a cluster are attached via a QLogic HBA card to the SAN.
> The setup is such that normally only one server in the cluster activates
> the VGs and mounts the volumes, but we have a failover setup, so that if
> there is a problem on one machine, that machine unmounts the file systems,
> deactivates the volumes, and then the backup machine scans for volumes,
> activates them and mounts them.  We've tested the failover scenario
> extensively and it works fine moving the volumes back and forth between
> the 2 machines.  But, perhaps after 2 switches and 2 machines doing a
> "vgscan", some sort of inconsistency is caused?!?!  Perhaps some info is
> different from the scan on each machine, which is causing the issue.  But,
> I would think that the information should be
>  identical on both servers in the cluster.
> 
> Any additional thoughts on that?
> 
> Thanks,
> Dave
> 
> ----- Original Message ----
> From: Roger Lucas <roger planbit co uk>
> To: Dave <davo_muc yahoo com>; LVM general discussion and development
> <linux-lvm redhat com>
> Sent: Friday, July 28, 2006 11:47:17 AM
> Subject: RE: [linux-lvm] LVM1 - "VGDA in kernel and lvmtab are NOT
> consistent"error following lvm operations
> 
> Small world - I was chasing a similar problem this morning with LVM2.
> 
> I don't know if your problem is the same as mine, but...
> 
> In my system I am using LVM within Dom0.  I am then creating "disks" for
> the
> DomUs from the LVM partitions.  E.g.
> 
> (Hydra = Dom0)
> 
> root hydra:~# pvs
>   PV         VG    Fmt  Attr PSize   PFree
>   /dev/hda3  xenvg lvm2 a-   176.05G 162.43G
> root hydra:~# vgs
>   VG    #PV #LV #SN Attr   VSize   VFree
>   xenvg   1   7   0 wz--n- 176.05G 162.43G
> root hydra:~# lvs
>   LV           VG    Attr   LSize   Origin Snap%  Move Log Copy%
>   backupimage  xenvg -ri-ao 512.00M
>   harpseal     xenvg -wi-ao   5.00G
>   harpseal-lvm xenvg -wi-ao   1.00G
>   octopus      xenvg -wi-ao   1.00G
>   octopus-lvm  xenvg -wi-ao   1.00G
>   tarantula    xenvg -wi-ao   5.00G
>   userdisk     xenvg -wi-a- 128.00M
> root hydra:~# cat /etc/xen/octopus
> kernel = "/boot/vmlinuz-2.6.16-xen"
> ramdisk = "/boot/initrd.img-2.6.16-xen"
> memory = 128
> name = "octopus"
> # Remember in Xen we are limited to three virtual network interfaces per
> DomU...
> vif = ['mac=aa:00:00:00:00:e7,bridge=xenbr0',
> 'mac=aa:00:00:00:01:01,bridge=xenbr1',
> 'mac=aa:00:00:00:02:01,bridge=xenbr2']
> disk = ['phy:/dev/xenvg/octopus,hda1,w','phy:/dev/xenvg/octopus-
> lvm,hda2,w']
> hostname = "octopus"
> root = "/dev/hda1 ro"
> extra = "4"
> root hydra:~#
> 
> Now, the DomU is also using LVM:
> 
> root octopus:~# pvs
>   PV         VG      Fmt  Attr PSize    PFree
>   /dev/hda2  storage lvm2 a-   1020.00M 380.00M
> root octopus:~# vgs
>   VG      #PV #LV #SN Attr   VSize    VFree
>   storage   1   2   0 wz--n- 1020.00M 380.00M
> root octopus:~# lvs
>   LV          VG      Attr   LSize   Origin Snap%  Move Log Copy%
>   backupimage storage -ri-ao 512.00M
>   userdisk    storage -wi-a- 128.00M
> root octopus:~#
> 
> 
> Now we have the problem!  When the Dom0 scans for LVs, it will look on
> /dev/hda3 and find the "xenvg" and all its LVs.  It will then look
> _inside_
> these LVs and find the "/dev/storage" group that really belongs to the
> DomU.
> At this point, you have two machines accessing the same LV, which is
> "bad".
> 
> The solution is to restrict the Dom0 LVM to only use the devices that we
> know are for scanning.  This is not the default behaviour - the default
> behaviour (at least under Debian/(K)Ubuntu) is to scan pretty much every
> block device in /dev - and this why the problem occurs.
> 
> I changed by Dom0 LVM configuration to only scan /dev/hda as below.
> 
> root hydra:~# cat /etc/lvm/lvm.conf
> devices {
>     dir = "/dev"
>     scan = [ "/dev" ]
>     filter =[ "a|/dev/hda|", "r|.*|" ]
>     cache = "/etc/lvm/.cache"
>     write_cache_state = 1
>     sysfs_scan = 1
>     md_component_detection = 1
> }
> /snip/
> root hydra:~#
> 
> I'm not an LVM expert and I cannot tell enough from your e-mail to know if
> this is your problem, but hopefully this will help you (or maybe someone
> else).
> 
> BR,
> 
> Roger
> 
> 
> > -----Original Message-----
> > From: linux-lvm-bounces redhat com [mailto:linux-lvm-bounces redhat com]
> > On Behalf Of Dave
> > Sent: 28 July 2006 10:39
> > To: linux-lvm redhat com
> > Subject: [linux-lvm] LVM1 - "VGDA in kernel and lvmtab are NOT
> > consistent"error following lvm operations
> >
> > Hello,
> >
> > I've been using LVM (1.08), which comes by default with RedHat
> AS3update5,
> > for over a year now and am consistently running into a problem.  I hope
> > there are still some LVM version 1 users out there who have some
> knowledge
> > about this!!
> >
> > After a reboot, LVM typically functions as expected, however,
> oftentimes,
> > after some LVM operations, I get the following sequence:
> >
> > [root mucrrp10 vb]# vgdisplay
> > vgdisplay -- ERROR: VGDA in kernel and lvmtab are NOT consistent; please
> > run vgscan
> >
> > [root mucrrp10 vb]# vgscan
> > vgscan -- reading all physical volumes (this may take a while...)
> > vgscan -- found active volume group "prdxptux"
> > vgscan -- found exported volume group "prdtuxPV_EXP"
> > vgscan -- "/etc/lvmtab" and "/etc/lvmtab.d" successfully created
> > vgscan -- WARNING: This program does not do a VGDA backup of your volume
> > groups
> >
> > [root mucrrp10 vb]# vgdisplay
> > vgdisplay -- ERROR: VGDA in kernel and lvmtab are NOT consistent; please
> > run vgscan
> >
> > This is troublesome because it makes it difficult to reliably use
> certain
> > LVM commands and trust their results.  I need to minimize reboots as
> much
> > as possible.
> >
> > Any help in understanding the cause of this problem, and how to resolve
> > it, or avoid it, are greatly appreciated!!
> >
> > Here is some version info about the system and software (I can provide
> > more information if needed):
> >
> > [root mucrrp10 vb]# cat /etc/redhat-release
> >  Red Hat Enterprise Linux AS release 3 (Taroon Update 5)
> >  [root mucrrp10 vb]# uname -a
> >  Linux mucrrp10 2.4.21-32.ELsmp #1 SMP Fri Apr 15 21:17:59 EDT 2005 i686
> > i686 i386 GNU/Linux
> >  [root mucrrp10 vb]# rpm -qa|grep lvm
> >  lvm-1.0.8-12.2
> >
> > Thanks in advance for any assistance.
> > Regards,
> > David
> >
> >
> >
> >
> > _______________________________________________
> > 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/
> 
> 
> 



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