Re: md: bug in file md.c, line 1440 (2.4.22)

On Saturday August 30, andre@tomt.net wrote:

Heya :-)

Having a funny showstopper problem here with md, the autostart fails 
miserably with "md: bug in file md.c, line 1440"

Here's the story;

and a sad one it is...

md:	**********************************
md:	* <COMPLETE RAID STATE PRINTOUT> *
md:	**********************************
md5: <hda9> array superblock:
md:  SB: (V:0.90.0) ID:<80012e77.b449af86.6bccffae.ddda9474> CT:3e4caa02
md:     L1 S24394560 ND:-22 RD:2 md5 LO:0 CS:32768
md:     UT:3f50117d ST:1 AD:2 WD:2 FD:-24 SD:0 CSUM:a62f39ca E:0000006d
     D  0:  DISK<N:0,hdc9(22,9),R:0,S:6>
     D  1:  DISK<N:1,hda9(3,9),R:1,S:6>
     D  2:  DISK<N:2,[dev 00:00](0,0),R:2,S:9>
     D  3:  DISK<N:0,[dev 00:00](0,0),R:0,S:9>
     D  4:  DISK<N:0,[dev 00:00](0,0),R:0,S:9>

Your problem is that these extra slots (N:0) are flagged as failed
(S:9) and this confuses md.c.

If you get mdadm 1.3.0 and apply the three patches that can be found
in
   http://cgi.cse.unsw.edu.au/~neilb/source/mdadm/patch/applied/

and then stop the array and use:
   mdadm --assemble --update=summaries /dev/md5 /dev/sda9 /dev/sdc9

then it should fix things up for you.
You will need to do a similar thing for all of the arrays.
This will be difficult for md2 as it is 'root'.  You will need to boot
a rescue disc to fix this one.

I have not idea how it got the failed flag.

NeilBrown