[linux-lvm] ReCreating the 1st 512 bytes of PV

lvm-list.mail at NEX-consult.com lvm-list.mail at NEX-consult.com
Mon Mar 1 10:56:03 UTC 2004


{...CUT...} 


>>**************** 
>> 
>>I?ve found "/etc/lvmtab.d/vg00", "/etc/lvmconf/vg00.conf" and 
>>"/etc/lvmtab" on a backup 
>>(which doesn?t contain my real important data) 
>> 
>>But: 
>> 
>>root 0[hda7]# vgcfgrestore -n vg00 /dev/hda5 
>>vgcfgrestore -- INFO: using backup file "/etc/lvmconf/vg00.conf" 
>>vgcfgrestore -- ERROR: different structure size stored in 
>>"/etc/lvmconf/vg00.conf" than expected in file vg_cfgrestore.c [line 
>>120] 
>>vgcfgrestore -- ERROR "vg_cfgrestore(): read" restoring volume group 
>>"vg00" 
>>**************** 
> 
>This must be a rather old metadata backup when you hit this problem 
>of changed structure sizes. 
>You need an actual metadata backup or the vgcfgrestore you took the backup with 
>in order to restore the old one. 
> 
>> 
>>.. to locate the file-systems directly on /dev/hda5/, "dd" them into a 
>>file and mount it as loop-back-device works 
>>slightly, but contains only a few usable data (after fsck.reiserfs 
>>--rebuilt-tree), mostly only files with crap content. 
> 
>You started with the wrong offset and/or have a non-trivial mapping 
>where logical extents and physical extents ar not in order. 

I guess, it's in a mixed order... Why ? 


{...CUT...} 

> 
> 
>Summary: 
> 
>a) if you have an *actual* metadata backup, restore it. 

I´ve only the backups which I got from "dd". (I thought first, I got it 
from a backup CD) 

>b) if not, use the LVM tool version you used for the metadata backup 
>  to vgcfgrestore it (mind to "pvcreate -ff /dev/hda5" before vgcfgrestore). 

*** 
dd if=/dev/zero of=/dev/hda5 bs=512 count=1 
1+0 Records ein 
1+0 Records aus 
512 bytes transferred in 0,005832 seconds (87790 bytes/sec) 

*** 
pvcreate -ff /dev/hda5 
pvcreate -- WARNING: forcing physical volume creation on "/dev/hda5" 
pvcreate -- physical volume "/dev/hda5" successfully created 

*** 
0000000: 484d 0100 0000 0000 0004 0000 0010 0000  HM.............. 
0000010: 0010 0000 0000 0000 0000 0000 0000 0000  ................ 
0000020: 0000 0000 0000 0000 0000 0000 674b 346c  ............gK4l 
0000030: 3630 484e 3251 5953 776a 714b 4d38 5265  60HN2QYSwjqKM8Re 
0000040: 7030 7566 7772 4671 4163 7350 0000 0000  p0ufwrFqAcsP.... 
0000050: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000060: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000070: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000080: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000090: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00000a0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00000b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00000c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00000d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00000e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00000f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000100: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000110: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000120: 0000 0000 0000 0000 0000 0000 4b6e 6f70  ............Knop 
0000130: 7069 7831 3037 3831 3337 3234 3600 0000  pix1078137246... 
0000140: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000150: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000160: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000170: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000180: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
0000190: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00001a0: 0000 0000 0000 0000 0000 0000 0300 0000  ................ 
00001b0: 0000 0000 0000 0000 0200 0000 0cb6 fd00  ................ 
00001c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00001d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00001e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
00001f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................ 
*** 
root at 0[lvmconf]# pvscan 
pvscan -- reading all physical volumes (this may take a while...) 
pvscan -- inactive PV "/dev/hda5" is in no VG  [7.93 GB] 
pvscan -- total: 1 [7.93 GB] / in use: 0 [0] / in no VG: 1 [7.93 GB] 

*** 
vgcfgrestore -f /mnt/hda7/20040229_vg-test/1/lvmconf/vg00.conf -n vg00 
-t -v /dev/hda5 

vgcfgrestore -- locking logical volume manager 
vgcfgrestore -- restoring volume group "vg00" from 
"/mnt/hda7/20040229_vg-test/1/lvmconf/vg00.conf" 
vgcfgrestore -- checking existence of 
"/mnt/hda7/20040229_vg-test/1/lvmconf/vg00.conf" 
vgcfgrestore -- reading volume group data for "vg00" from 
"/mnt/hda7/20040229_vg-test/1/lvmconf/vg00.conf" 
vgcfgrestore -- ERROR: different structure size stored in 
"/mnt/hda7/20040229_vg-test/1/lvmconf/vg00.conf" than expected in file 
vg_cfgrestore.c [line 120] 
vgcfgrestore -- ERROR "vg_cfgrestore(): read" restoring volume group 
"vg00" 

*** 
pvdata /dev/hda5 

--- NEW Physical volume --- 
PV Name              /dev/hda5 
VG Name 
PV Size              7.93 GB [16627212 secs] 
PV#                  0 
PV Status            NOT available 
Allocatable          NO 
Cur LV                0 
PE Size (KByte)      0 
Total PE              0 
Free PE              0 
Allocated PE          0 
PV UUID              gK4l60-HN2Q-YSwj-qKM8-Rep0-ufwr-FqAcsP 

--- Volume group --- 
VG Name 
VG Access            read/write 
VG Status            NOT available/resizable 
VG #                  0 
MAX LV                256 
Cur LV                3 
Open LV              0 
MAX LV Size          255.99 GB 
Max PV                256 
Cur PV                1 
Act PV                1 
VG Size              7.92 GB 
PE Size              4 MB 
Total PE              2028 
Alloc PE / Size      2028 / 7.92 GB 
Free  PE / Size      0 / 0 
VG UUID              xe1EZa-92lV-3Nyq-BX36-z9Te-7EcA-1vonap 

--- List of logical volumes --- 

pvdata -- logical volume struct at offset  0 is inconsistent 
pvdata -- logical volume struct at offset  1 is empty 
... 
pvdata -- logical volume struct at offset  12 is empty 
pvdata -- logical volume struct at offset  13 is inconsistent 
... 
pvdata -- logical volume struct at offset  25 is inconsistent 
pvdata -- logical volume struct at offset  26 is empty 
... 
pvdata -- logical volume struct at offset 124 is empty 
... 
pvdata -- logical volume struct at offset 139 is inconsistent 
pvdata -- logical volume struct at offset 140 is empty 
... 
pvdata -- logical volume struct at offset 255 is empty 

--- List of physical volume UUIDs --- 

Segmentation fault 

*** 
==> You can find "lvmconf" on my site: 
http://www.NEX-consult.com/vg00-cfg.from-dd.tar.gz 
Could you please check it if it's usable ? 

*** 



>c) if you have a sequential 1:1 mapping, find the correct offset of the 
>  first extent and retry dd'ing data off hda5 
> 

I´m afraid, it´s not sequential. 



Thanks 
Tobias




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