I have here a raid md4 with 1.0 superblock consisting of sda3 and sdb3 which I want to convert to 0.9X superblocks. As the first step I wanted to zero the old superblock: root@sidux:~# cat /proc/mdstat Personalities : [raid1] ... md4 : active raid1 sda3[0] sdb3[1] 2008112 blocks super 1.0 [2/2] [UU] ... root@sidux:~# mdadm --stop /dev/md4 mdadm: stopped /dev/md4 mdadm: Couldn't open /dev/md4 for write - not zeroing root@sidux:~# ll /dev/md4 ls: cannot access /dev/md4: No such file or directory root@sidux:~# ll /dev/md/4 lrwxrwxrwx 1 root root 6 2010-03-07 00:42 /dev/md/4 -> ../md4 root@sidux:~# ll /dev/md md/ md0 md1 md2 md3 md5 root@sidux:~# ll -d /dev/md* drwxr-xr-x 2 root root 100 2010-03-07 00:42 /dev/md brw-rw---- 1 root disk 9, 0 2010-03-07 00:42 /dev/md0 brw-rw---- 1 root disk 9, 1 2010-03-07 00:42 /dev/md1 brw-rw---- 1 root disk 9, 2 2010-03-07 11:36 /dev/md2 brw-rw---- 1 root disk 9, 3 2010-03-07 00:42 /dev/md3 brw-rw---- 1 root disk 9, 5 2010-03-07 00:42 /dev/md5 root@sidux:~# mknod /dev/md4 b 9 4 root@sidux:~# ll -d /dev/md* drwxr-xr-x 2 root root 100 2010-03-07 00:42 /dev/md brw-rw---- 1 root disk 9, 0 2010-03-07 00:42 /dev/md0 brw-rw---- 1 root disk 9, 1 2010-03-07 00:42 /dev/md1 brw-rw---- 1 root disk 9, 2 2010-03-07 11:36 /dev/md2 brw-rw---- 1 root disk 9, 3 2010-03-07 00:42 /dev/md3 brw-r--r-- 1 root root 9, 4 2010-03-07 13:23 /dev/md4 brw-rw---- 1 root disk 9, 5 2010-03-07 00:42 /dev/md5 root@sidux:~# mdadm --zero-superblock /dev/md4 mdadm: Unrecognised md component device - /dev/md4 Any hint is appreciated. Reproducible: Always
root@sidux:~# mdadm --zero-superblock /dev/sda3 root@sidux:~# mdadm --zero-superblock /dev/sdb3 root@sidux:~# mdadm --create /dev/md4 --level=1 --raid-devices=2 --metadata=0.90 /dev/sda3 /dev/sdb3 mdadm: /dev/sda3 appears to contain an ext2fs file system size=2008112K mtime=Sun Mar 7 11:35:36 2010 mdadm: /dev/sdb3 appears to contain an ext2fs file system size=2008112K mtime=Sun Mar 7 11:35:36 2010 Continue creating array? y mdadm: array /dev/md4 started. seems to work.
Thanks for reporting this. Assigning to base-system for further investigation.
i think the behavior you show is correct. dont superblocks exist on individual pieces and not the assembled device ? the error message you showed: mdadm: Unrecognised md component device - /dev/md4 and that's because /dev/md# is not a component device when you used the option on an actual component device, it seems to have worked fine
