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[linux-lvm] The way i use to ensure the VG map (Need help)



Hello,

Still with my huge problems (regular fs corruption inside KVM guests). I use a shared LVM on a SAN storage, without CLVM :(.

I would like to be sure I don't have LVs overlaping each other.
I ran vgck SATA6To, that doesn't produce output, so I expect everything is good on disk.

So, i tried to do the same on device mapper with the following script :
#!/usr/bin/perl
while(<>) {
#   SATA6To-vm--316--disk--3: 0 8388608 linear 152:16 31457664
   my ( $vol, $vol_start, $vol_size, $alloc, $raid, $pos ) = split( /\s/, $_ );

   if( $vol =~ /^sata6to-vm--(\d{3})--disk--(\d)/i ) {
       my $vm = $1;
       my $disk = $2;

       if( defined $vms->{ $vm }->{ $disk } ) {
           die "HUGE PROBLEM: VM $vm DISK $disk ALREADY EXISTS!!!\n";
       }

       my $start = $pos;
       my $stop  = $pos+$vol_size-1;

       $vms->{ $vm }->{ $disk } = {
           start => $start,
           stop  => $stop, 
       };

       if( defined $map->{ $start } ) {
           warn "VM $vm/$disk WANTS TO START ON " . Dump $map->{ $start };
       }
       $map->{ $start } = { "$vm/$disk" => 'start' };

       if( defined $map->{ $stop } ) {
           warn "VM $vm/$disk WANTS TO STOP ON " . Dump $map->{ $stop };
       }
       $map->{ $stop }  = { "$vm/$disk" => 'stop' };
   }
}

for my $pos ( sort{ $a <=> $b } keys %$map ) {

   printf( "%010d\t%s\t%s\n", $pos, ( %{ $map->{ $pos } } ) );

}

It produces this kind of output :
0000000384	316/1	start
0020971903	316/1	stop
0020971904	316/2	start
0031457663	316/2	stop

We check that no LV would start before a previous LV stop. By the way I did on the whole cluster to ensure I get the same result on the nodes.

Is it a good way to check the consistancy between LVM metadata and DeviceMapper ?

Your help will be precious, I'm going mad.




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