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[linux-lvm] Re: need to restore corrupted VG, help needed!



Heinz, Thanks for your reply!

Ok, the real scenario is following. I had hdg5 and hde5 on linux software
raid 1 mirror, so /dev/md1 was made up of /dev/hdg5 and /dev/hde5. One of
the HDDs was acting strange (decreased somehow system performance), so I
decided to break this mirror, then removed hdg from it and then made
pvmove from md1 -> hde. The performance problem was solved, because other
hdd was removed from usage. I left the system alone for a while and
because I didn't have physical access to server. After couple of days I
removed physically this drive. But after restart the system didn't come
up. So, as I needed also to update the system (and I had time for this), I
decided to reinstall completely new system (RH 8.0), it was easier than
patch and migrate the old one. After the new system was up and running, I
tried to use vgimport, but it gave me error sth like VG "vg" on hdg5 isn't
exported. Somehow (I guess I made foolish to try this) I succeeded to put
"vg" on hdg5 on exported status. But I think that this exporting didn't
cause the problem, I guess that the problem appeared while I was breaking
the original mirror and pvmove? I never hadn't two PV's in this VG, so I
guess that LVM somehow messed up PV# and maybe captured another UUID from
separated mirror? So, I confirm that I never had actually this VG running
on second PV, so all data must reside on this PV. And now, the question
still remains, how could I remove this "fake" first PV UUID so that I
could import this PV and use data from these LV's? I've made also the map
of output of "pvdata -E /dev/hde5", could I use this somehow to extract
data from HDD? If I know the order of LEs on PE, could I have some benefit
of this data. Could I for exaple, copy these PEs with dd to separate disk
and just mount the filesystem from it then?

> From: "Heinz J . Mauelshagen" <mauelshagen sistina com>
> To: linux-lvm sistina com
> Subject: Re: [linux-lvm] need to restore corrupted VG, help needed!
> Reply-To: linux-lvm sistina com
>
>
> Liivo,
> pvdata shows that you had _two_ physical volumes in your volume group
> before and that "vg" is exported?
>
> Why is it exported when your other drive crashed and where's the other
> physical volume belonging to "vg"? Was it eventually on the dead drive?
> In that case it is pretty unlikely that you can retrieve a lot of your
> logical volume date anyways. Even if you replace that drive, you won't
> get that data back which went down the drain woth it.
>
> If you don't find the other physical volume with "pvscan -u" (look for
> UUID Zy48rM-UOIi-0gP7-TvjK-apfK-4oJ1-0rvV2b) and
> if my assumptions are correct you want to go for a restore.
> Hopefully you've got a recent backup.
>
> Regards,
> Heinz    -- The LVM Guy --
>
>
> On Tue, Nov 12, 2002 at 11:11:23AM +0200, Liivo Liivrand wrote:
>> Hello All!
>>
>> I had a disk crash on my system and now I need to have my VG back, but
>> how? I had two HDDs, one containing root partition and one with LVM.
>> HDD with root partition crashed and backup was too old to restore :-(
>> Now I installed new system (RedHat 8.0) and need urgently to have my
>> files from old LVs, but I can't. Please help me! Look down, I think
>> that problem is in PV#, but how can I change it?
>>
>> Output follows:
>> --- Cut ---
>> # fdisk -l /dev/hde
>>
>> Disk /dev/hde: 16 heads, 63 sectors, 79780 cylinders
>> Units = cylinders of 1008 * 512 bytes
>>
>>    Device Boot    Start       End    Blocks   Id  System
>> /dev/hde1   *         1       203    102280+  fd  Linux raid
>> autodetect /dev/hde2           204      1243    524160   8e  Linux LVM
>> /dev/hde3          1244      1446    102312   fd  Linux raid
>> autodetect /dev/hde4          1447     79780  39480336   85  Linux
>> extended /dev/hde5          1447     79780  39480304+  8e  Linux LVM
>>
>> # vgscan
>> vgscan -- reading all physical volumes (this may take a while...)
>> vgscan -- found active volume group "sys"
>> vgscan -- found exported volume group "vgPV_EXP"
>> vgscan -- ERROR "vg_read_with_pv_and_lv(): current PV" can't get data
>> of volume group "vg" from physical volume(s)
>> vgscan -- "/etc/lvmtab" and "/etc/lvmtab.d" successfully created
>> vgscan -- WARNING: This program does not do a VGDA backup of your
>> volume groups
>>
>> # vgimport -f vg /dev/hde5
>> vgimport -- ERROR: wrong number of physical volumes to import volume
>> group "vg"
>>
>> # pvdisplay /dev/hde5
>> --- Physical volume ---
>> PV Name               /dev/hde5
>> VG Name               vg
>> PV Size               37.65 GB [78960609 secs] / NOT usable 4.18 MB
>> [LVM: 161 KB]
>> PV#                   2
>> PV Status             NOT available
>> Allocatable           yes
>> Cur LV                0
>> PE Size (KByte)       4096
>> Total PE              9637
>> Free PE               9637
>> Allocated PE          0
>> PV UUID               7OuTtg-ci2d-4jcK-zhlO-0W5F-YvlT-lzkXMp
>>
>> # pvdata -v /dev/hde5
>> --- Physical volume ---
>> PV Name               /dev/hde5
>> VG Name               vg
>> PV Size               37.65 GB [78960609 secs] / NOT usable 4.18 MB
>> [LVM: 161 KB]
>> PV#                   2
>> PV Status             NOT available
>> Allocatable           yes
>> Cur LV                0
>> PE Size (KByte)       4096
>> Total PE              9637
>> Free PE               9637
>> Allocated PE          0
>> PV UUID               7OuTtg-ci2d-4jcK-zhlO-0W5F-YvlT-lzkXMp
>>
>> --- Volume group ---
>> VG Name
>> VG Access             read/write
>> VG Status             NOT available/resizable
>> VG #                  0
>> MAX LV                255
>> Cur LV                11
>> Open LV               0
>> MAX LV Size           255.99 GB
>> Max PV                255
>> Cur PV                2
>> Act PV                2
>> VG Size               75.29 GB
>> PE Size               4 MB
>> Total PE              19274
>> Alloc PE / Size       9583 / 37.43 GB
>> Free  PE / Size       9691 / 37.86 GB
>
> <SNIP>
>
>> pvdata -- logical volume struct at offset 254 is empty
>> --- List of physical volume UUIDs ---
>>
>> 001: Zy48rM-UOIi-0gP7-TvjK-apfK-4oJ1-0rvV2b
>> 002: 7OuTtg-ci2d-4jcK-zhlO-0W5F-YvlT-lzkXMp
>>
>> --- Cut ---
>>
>>
>>
>> _______________________________________________
>> linux-lvm mailing list
>> linux-lvm sistina com
>> http://lists.sistina.com/mailman/listinfo/linux-lvm
>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
> *** Software bugs are stupid.
>     Nevertheless it needs not so stupid people to solve them ***
>
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>
> Heinz Mauelshagen                                 Sistina Software Inc.
> Senior Consultant/Developer                       Am Sonnenhang 11
>                                                   56242 Marienrachdorf
> Germany
> Mauelshagen Sistina com                           +49 2626 141200
>                                                        FAX 924446
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-







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