[linux-lvm] Major problems after soft raid 5 failure
Colin Faber
cfaber at gmail.com
Thu Jan 15 01:15:38 UTC 2009
Hi,
malahal at us.ibm.com wrote:
> Colin Faber [cfaber at gmail.com] wrote:
>
>> was unavailable. After searching around I kept coming back to suggestions
>> stating that removal of the missing device from the volume group was the
>> solution to getting thing back online again. So using 'vgreduce
>> --removemissing raid' then 'lvchange -ay raid' to update the changes -
>> Neither command errored and vgreduce noted that 'raid' was not available
>> again.
>>
>
> Since your LV (array) is most likely allocated on md1 that disappeared,
> you really want --partial (lvm command) rather than --removemissing.
> Your metadata is updated and any knowledge about 'array' LV is now
> almost gone due to the above 'vgreduce'. I say almost gone because it
> might be there but you really need true LVM expertise now!
>
> Did you save a copy of your old LVM metadata before the reboot? See your
> /etc/lvm/backup/raid has any reference to 'array' LV at all.
>
Yes, it's still there (well /etc/lvm/archive/). So how do I back out of
this after I've already run removemissing? If I try and restore the old
vg backup it just tells me that it can't restore it because the uuid is
missing for md1.
By the way, thank you very much for the response. Any suggestions and
help are greatly welcome.
-cf
> --Malahal.
>
>
>> So as it stands now I have no logical volume, I have a volume group and I
>> have a functional md0 array. If I dump the first 50 or so megs of the md0
>> raid array I can see the volume group information, as well as the lv
>> information including various bits of file system information.
>>
>> At this point I'm wondering can I recover the logical volume and recover
>> this 1.8TB of data.
>>
>> For completeness here is the results of various display and scan commands:
>>
>> root at Aria:/dev/disk/by-id# pvscan
>> PV /dev/md0 VG raid lvm2 [1.82 TB / 1.82 TB free]
>> Total: 1 [1.82 TB] / in use: 1 [1.82 TB] / in no VG: 0 [0 ]
>>
>> root at Aria:/dev/disk/by-id# pvdisplay
>> --- Physical volume ---
>> PV Name /dev/md0
>> VG Name raid
>> PV Size 1.82 TB / not usable 2.25 MB
>> Allocatable yes
>> PE Size (KByte) 4096
>> Total PE 476933
>> Free PE 476933
>> Allocated PE 0
>> PV UUID oI1oXp-NOSk-BJn0-ncEN-HaZr-NwSn-P9De9b
>>
>> root at Aria:/dev/disk/by-id# vgscan
>> Reading all physical volumes. This may take a while...
>> Found volume group "raid" using metadata type lvm2
>>
>> root at Aria:/dev/disk/by-id# vgdisplay
>> --- Volume group ---
>> VG Name raid
>> System ID
>> Format lvm2
>> Metadata Areas 1
>> Metadata Sequence No 11
>> VG Access read/write
>> VG Status resizable
>> MAX LV 0
>> Cur LV 0
>> Open LV 0
>> Max PV 0
>> Cur PV 1
>> Act PV 1
>> VG Size 1.82 TB
>> PE Size 4.00 MB
>> Total PE 476933
>> Alloc PE / Size 0 / 0
>> Free PE / Size 476933 / 1.82 TB
>> VG UUID quRohP-EcsI-iheW-lbU5-rBjO-TnqS-JbjmZA
>>
>> root at Aria:/dev/disk/by-id# lvscan
>> root at Aria:/dev/disk/by-id#
>>
>> root at Aria:/dev/disk/by-id# lvdisplay
>> root at Aria:/dev/disk/by-id#
>>
>>
>> Thank you.
>>
>> -cf
>>
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>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>
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