Re: How to recover after md crash during reshape?

[Andras Tantos <andras@tantosonline.com>]

Thanks again Phil!

I'm almost there...

 >>     [ 5859.527778] EXT4-fs (md1): bad geometry: block count 1831419920
 >> exceeds size of device (1831419760 blocks)
 >
 >Yep. You'll need to use the --size option on a create. Note that it
 >specifies the amount of each device to use, not the overall array size.
 >According to "man mdadm", its units is k == 1024 bytes.  Use the exact
 >size from your original => --size=1465135936

When I try to do that, I get the following message:

     root@bazsalikom:~# mdadm --create --assume-clean --verbose 
--metadata=1.0 --raid-devices=7 --size=1465135936 --chunk=64 --level=6 
/dev/md1 /dev/sde2 /dev/sdc2 /dev/sdf1 /dev/sdd1 /dev/sdb1 /dev/sdg1 
/dev/sdh2
     mdadm: layout defaults to left-symmetric
     mdadm: /dev/sde2 appears to contain an ext2fs file system
         size=-1216020180K  mtime=Wed Dec  8 11:55:07 1954
     mdadm: /dev/sde2 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdc2 appears to contain an ext2fs file system
         size=-1264254912K  mtime=Sat Jul 18 15:26:57 2015
     mdadm: /dev/sdc2 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdf1 is smaller than given size. 1465135808K < 
1465135936K + metadata
     mdadm: /dev/sdd1 is smaller than given size. 1465135808K < 
1465135936K + metadata
     mdadm: /dev/sdb1 is smaller than given size. 1465135808K < 
1465135936K + metadata
     mdadm: /dev/sdg1 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdh2 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: create aborted

To be able to re-assemble the array, I *have* to specify metadata 
version 0.9:

     root@bazsalikom:~# mdadm --create --assume-clean --verbose 
--metadata=0.9 --raid-devices=7 --size=1465135936 --chunk=64 --level=6 
/dev/md1 /dev/sde2 /dev/sdc2 /dev/sdf1 /dev/sdd1 /dev/sdb1 /dev/sdg1 
/dev/sdh2
     mdadm: layout defaults to left-symmetric
     mdadm: /dev/sde2 appears to contain an ext2fs file system
         size=-1216020180K  mtime=Wed Dec  8 11:55:07 1954
     mdadm: /dev/sde2 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdc2 appears to contain an ext2fs file system
         size=-1264254912K  mtime=Sat Jul 18 15:26:57 2015
     mdadm: /dev/sdc2 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdf1 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdd1 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdb1 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdg1 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: /dev/sdh2 appears to be part of a raid array:
         level=raid6 devices=7 ctime=Wed Oct 28 09:17:55 2015
     mdadm: largest drive (/dev/sdg1) exceeds size (1465135936K) by more 
than 1%
     Continue creating array? y
     mdadm: array /dev/md1 started.

Is this a problem? Can I upgrade my array to 1.0 metadata? Should I?

Andras