Re: Corrupted ext4 filesystem after mdadm manipulation error

["L.M.J" <linuxmasterjedi@free.fr>]

Up please :-(

Le Thu, 24 Apr 2014 07:05:48 +0200,
"L.M.J" <linuxmasterjedi@free.fr> a écrit :

> Hi,
> 
> For the third time, I had to change a failed drive from my home linux RAID5 box. Previous one went right and
> this time, I don't know what I did wrong, but I broke my RAID5. Well, at least, he didn't want to
> start. /dev/sdb was the failed drive /dev/sdc and /dev/sdd are OK.
> 
> I tried to reassemble the RAID with this command after I replace sdb and create a new partition :
> 
>  ~# mdadm -Cv /dev/md0 --assume-clean --level=5 --raid-devices=3 /dev/sdc1 /dev/sdd1 /dev/sdb1
> -> '-C' was not a good idea here 
> 
> Well, I guess I did an another mistake here, I should have done this instead :
>  ~# mdadm -Av /dev/md0 --assume-clean --level=5 --raid-devices=3 /dev/sdc1 /dev/sdd1 missing
> 
> Maybe this wipe out my data...
> Let's go futher, then, pvdisplay, pvscan, vgdisplay returns empty information 
> 
> Google helped me, and I did this :
>  ~# dd if=/dev/md0 bs=512 count=255 skip=1 of=/tmp/md0.txt
> 
> 	[..]
> 	physical_volumes {
> 		pv0 {
> 			id = "5DZit9-6o5V-a1vu-1D1q-fnc0-syEj-kVwAnW"
> 			device = "/dev/md0"
> 			status = ["ALLOCATABLE"]
> 			flags = []
> 			dev_size = 7814047360
> 			pe_start = 384
> 			pe_count = 953863
> 		}
> 	}
> 	logical_volumes {
> 
> 		lvdata {
> 			id = "JiwAjc-qkvI-58Ru-RO8n-r63Z-ll3E-SJazO7"
> 			status = ["READ", "WRITE", "VISIBLE"]
> 			flags = []
> 			segment_count = 1
> 	[..]
> 
> Since I saw lvm information, I guess I haven't lost all information yet...
> 
> I tried an unhoped command :
>  ~# pvcreate --uuid "5DZit9-6o5V-a1vu-1D1q-fnc0-syEj-kVwAnW"
> --restorefile /etc/lvm/archive/lvm-raid_00302.vg /dev/md0 Then,
> 
>  ~# vgcfgrestore lvm-raid
> 
>  ~# lvs -a -o +devices
>    LV     VG       Attr   LSize   Origin Snap%  Move Log Copy%  Convert  Devices
>    lvdata lvm-raid -wi-a- 450,00g                                                     /dev/md0(148480)
>    lvmp   lvm-raid -wi-a-  80,00g                                                     /dev/md0(263680)
> Then :
>  ~# lvchange -ay /dev/lvm-raid/lv*
> 
> I was quite happy until now.
> Problem appears now when I try to mount those 2 LV (lvdata & lvmp) as ext4 partition :
>  ~# mount /home/foo/RAID_mp/
> 
>  ~# mount | grep -i mp
>       /dev/mapper/lvm--raid-lvmp on /home/foo/RAID_mp type ext4 (rw)
> 
>  ~# df -h /home/foo/RAID_mp
>       Filesystem                            Size  Used Avail Use%   Mounted on
>       /dev/mapper/lvm--raid-lvmp   79G   61G   19G  77%   /home/foo/RAID_mp
> 
> Here is the big problem
>  ~# ls -la /home/foo/RAID_mp
>       total 0
> 
> I did a LVM R/W snapshot on the /dev/mapper/lvm--raid-lvmp LV, I fsck it. I recover 50% of the files only,
> all located in lost-+found/ directory with names heading with #xxxxx.
> 
> I would like to know if there is a last chance to recover my data ?
> 
> Thanks
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