Recovering data from an incorrectly re-created mdadm RAID1 array
I had a functioning mdadm RAID1 array in an old server, but in my efforts to relocate it in a new server erroneously used --create instead of --assemble. I realised within minutes that it wouldn't mount and stopped the resync and have subsequently removed one of the drives while I try to recover data.
The array will start (I'm keeping it degraded and read-only for now) but /dev/md0 isn't recognised by dumpe2fs.
Looking at other questions here I see indication that if the new array was created with the same metadata version then it should be possible to recover, but as far as I can tell both old and new servers used 1.2, so that's proved a dead end.
However, if I use testdisk on /dev/sdb1 (the RAID partition), a deep search can find my ext4 partition data and allows me to list the files I would expect to see. For example:
Disk /dev/sdb1 - 3000 GB / 2794 GiB - CHS 364801 255 63
Partition Start End Size in sectors
P Linux md 1.x RAID 0 0 1 364784 189 21 5860266888 [fileserver:0]
P ext4 16 80 63 364801 47 52 5860268936
>P ext4 16 81 2 364801 47 54 5860268936
Structure: Ok.
Keys T: change type, P: list files,
Enter: to continue
ext4 blocksize=4096 Large_file Sparse_SB, 3000 GB / 2794 GiB
... where the selected result shows me files if I hit "P".
I think what I'd like to do next is try to mount that filesystem (readonly) and see what is there, and maybe image it then e2fcsk it. However I can't convert testdisk's CHS values into something useful for dumpe2fs -o.
Am I taking the right approach? I need to get dumpe2fs to look at the filesystem that testdisk is showing me.
Note that I initially started this as another question; if asking a new question when the subject substantially moves on is bad form please advise.
https://unix.stackexchange.com/questions/468536/mdadm-autocreated-md126-md127-arrays-fine-but-corrupt-when-rebuilt-as-md0-md1
ext4 mdadm testdisk
edited 2 hours ago
Rui F Ribeiro
39.5k1479132
asked Sep 13 '18 at 11:36
Mark RogersMark Rogers
11
add a comment |
I had a functioning mdadm RAID1 array in an old server, but in my efforts to relocate it in a new server erroneously used --create instead of --assemble. I realised within minutes that it wouldn't mount and stopped the resync and have subsequently removed one of the drives while I try to recover data.
The array will start (I'm keeping it degraded and read-only for now) but /dev/md0 isn't recognised by dumpe2fs.
Looking at other questions here I see indication that if the new array was created with the same metadata version then it should be possible to recover, but as far as I can tell both old and new servers used 1.2, so that's proved a dead end.
However, if I use testdisk on /dev/sdb1 (the RAID partition), a deep search can find my ext4 partition data and allows me to list the files I would expect to see. For example:
Disk /dev/sdb1 - 3000 GB / 2794 GiB - CHS 364801 255 63
Partition Start End Size in sectors
P Linux md 1.x RAID 0 0 1 364784 189 21 5860266888 [fileserver:0]
P ext4 16 80 63 364801 47 52 5860268936
>P ext4 16 81 2 364801 47 54 5860268936
Structure: Ok.
Keys T: change type, P: list files,
Enter: to continue
ext4 blocksize=4096 Large_file Sparse_SB, 3000 GB / 2794 GiB
... where the selected result shows me files if I hit "P".
I think what I'd like to do next is try to mount that filesystem (readonly) and see what is there, and maybe image it then e2fcsk it. However I can't convert testdisk's CHS values into something useful for dumpe2fs -o.
Am I taking the right approach? I need to get dumpe2fs to look at the filesystem that testdisk is showing me.
Note that I initially started this as another question; if asking a new question when the subject substantially moves on is bad form please advise.
https://unix.stackexchange.com/questions/468536/mdadm-autocreated-md126-md127-arrays-fine-but-corrupt-when-rebuilt-as-md0-md1
ext4 mdadm testdisk
edited 2 hours ago
Rui F Ribeiro
39.5k1479132
asked Sep 13 '18 at 11:36
Mark RogersMark Rogers
11
add a comment |
I had a functioning mdadm RAID1 array in an old server, but in my efforts to relocate it in a new server erroneously used --create instead of --assemble. I realised within minutes that it wouldn't mount and stopped the resync and have subsequently removed one of the drives while I try to recover data.
The array will start (I'm keeping it degraded and read-only for now) but /dev/md0 isn't recognised by dumpe2fs.
Looking at other questions here I see indication that if the new array was created with the same metadata version then it should be possible to recover, but as far as I can tell both old and new servers used 1.2, so that's proved a dead end.
However, if I use testdisk on /dev/sdb1 (the RAID partition), a deep search can find my ext4 partition data and allows me to list the files I would expect to see. For example:
Disk /dev/sdb1 - 3000 GB / 2794 GiB - CHS 364801 255 63
Partition Start End Size in sectors
P Linux md 1.x RAID 0 0 1 364784 189 21 5860266888 [fileserver:0]
P ext4 16 80 63 364801 47 52 5860268936
>P ext4 16 81 2 364801 47 54 5860268936
Structure: Ok.
Keys T: change type, P: list files,
Enter: to continue
ext4 blocksize=4096 Large_file Sparse_SB, 3000 GB / 2794 GiB
... where the selected result shows me files if I hit "P".
I think what I'd like to do next is try to mount that filesystem (readonly) and see what is there, and maybe image it then e2fcsk it. However I can't convert testdisk's CHS values into something useful for dumpe2fs -o.
Am I taking the right approach? I need to get dumpe2fs to look at the filesystem that testdisk is showing me.
Note that I initially started this as another question; if asking a new question when the subject substantially moves on is bad form please advise.
https://unix.stackexchange.com/questions/468536/mdadm-autocreated-md126-md127-arrays-fine-but-corrupt-when-rebuilt-as-md0-md1
ext4 mdadm testdisk
edited 2 hours ago
Rui F Ribeiro
39.5k1479132
asked Sep 13 '18 at 11:36
Mark RogersMark Rogers
11
I had a functioning mdadm RAID1 array in an old server, but in my efforts to relocate it in a new server erroneously used --create instead of --assemble. I realised within minutes that it wouldn't mount and stopped the resync and have subsequently removed one of the drives while I try to recover data.
The array will start (I'm keeping it degraded and read-only for now) but /dev/md0 isn't recognised by dumpe2fs.
Looking at other questions here I see indication that if the new array was created with the same metadata version then it should be possible to recover, but as far as I can tell both old and new servers used 1.2, so that's proved a dead end.
However, if I use testdisk on /dev/sdb1 (the RAID partition), a deep search can find my ext4 partition data and allows me to list the files I would expect to see. For example:
Disk /dev/sdb1 - 3000 GB / 2794 GiB - CHS 364801 255 63
Partition Start End Size in sectors
P Linux md 1.x RAID 0 0 1 364784 189 21 5860266888 [fileserver:0]
P ext4 16 80 63 364801 47 52 5860268936
>P ext4 16 81 2 364801 47 54 5860268936
Structure: Ok.
Keys T: change type, P: list files,
Enter: to continue
ext4 blocksize=4096 Large_file Sparse_SB, 3000 GB / 2794 GiB
... where the selected result shows me files if I hit "P".
I think what I'd like to do next is try to mount that filesystem (readonly) and see what is there, and maybe image it then e2fcsk it. However I can't convert testdisk's CHS values into something useful for dumpe2fs -o.
Am I taking the right approach? I need to get dumpe2fs to look at the filesystem that testdisk is showing me.
Note that I initially started this as another question; if asking a new question when the subject substantially moves on is bad form please advise.
https://unix.stackexchange.com/questions/468536/mdadm-autocreated-md126-md127-arrays-fine-but-corrupt-when-rebuilt-as-md0-md1
ext4 mdadm testdisk
ext4 mdadm testdisk
edited 2 hours ago
Rui F Ribeiro
39.5k1479132
asked Sep 13 '18 at 11:36
Mark RogersMark Rogers
11
edited 2 hours ago
Rui F Ribeiro
39.5k1479132
asked Sep 13 '18 at 11:36
Mark RogersMark Rogers
11
edited 2 hours ago
Rui F Ribeiro
39.5k1479132
edited 2 hours ago
Rui F Ribeiro
39.5k1479132
edited 2 hours ago
Rui F Ribeiro
39.5k1479132
39.5k1479132
asked Sep 13 '18 at 11:36
Mark RogersMark Rogers
11
asked Sep 13 '18 at 11:36
Mark RogersMark Rogers
11
asked Sep 13 '18 at 11:36
Mark RogersMark Rogers
11
11
add a comment |
add a comment |
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