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When running update-grub on the newly installed Ubuntu 12.04 with an older software RAID (md), I get:

error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
Generating grub.cfg ...
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
Found linux image: /boot/vmlinuz-3.2.0-24-generic
Found initrd image: /boot/initrd.img-3.2.0-24-generic
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
Found linux image: /boot/vmlinuz-3.2.0-23-generic
Found initrd image: /boot/initrd.img-3.2.0-23-generic
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
Found memtest86+ image: /boot/memtest86+.bin
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
error: superfluous RAID member (5 found).
Found Debian GNU/Linux (5.0.9) on /dev/sdb1
Found Debian GNU/Linux (5.0.9) on /dev/sdc1
done

I would be less worried if the message would say warning: ..., but since it says error: ... I'm wondering what the problem is.

# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md2 : active raid1 sdc1[1] sdb1[0]
      48829440 blocks [2/2] [UU]

md3 : active raid1 sdc2[1] sdb2[0]
      263739008 blocks [2/2] [UU]

md1 : active raid5 sdg1[3] sdf1[2] sde1[1] sdh1[0] sdi1[4] sdd1[5](S)
      1250274304 blocks level 5, 64k chunk, algorithm 2 [5/5] [UUUUU]

unused devices: <none>

Do I have to worry or is this harmless?

btw: disregard the mentioning of Debian 5.0.9, that was the previously installed system and is going to be overwritten. It's on /dev/md2 actually.

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2 Answers 2

up vote 7 down vote accepted
+50

As mentioned here by Fussy Salsify this seems to be a bug of update-grub script with spare device in one of the RAID arrays. As mentioned here a patch has been applied and should come to Ubuntu at some time.

Boyd Stephen Smith Jr. said he thinks this error report may be just cosmetic here and Vladimir 'φ-coder/phcoder' Serbinenko submitted a patch that seems to just change the error report to "spares aren't implemented".

Also there is a bug report at launchpad (#816475) and a possible workaround that involves changing the partitioning. The importance of this bug is undecided at launchpad but looks like it caused some real problem to Björn Tillenius that could not upgrade/install grub. So looks like you should be careful.

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Thanks @desgua, the most important part of the question is, whether I need to worry (e.g. that my system becomes unbootable) due to the errors. Unfortunately even sifting over the bug report you linked, there seems to be no conclusive and/or authoritative statement as to whether I have to worry about it or not. +1 for the pointers already :) –  0xC0000022L May 22 '12 at 15:13
    
I have found some more info ;-) –  desgua May 23 '12 at 1:40
    
Thanks a bunch. The bounty well-deserved, I think. –  0xC0000022L May 23 '12 at 2:35

I was getting this error on ubuntu 12.04 both during upgrade-grub and briefly upon booting the PC but it was due to a misconfiguration on my side:

I had two partitions on two disks paired with mdadm using RAID1. After one disk crashed I replaced it and added a new one but at some point while entering the commands to add the partitions (mdadm --manage /dev/md... -a /dev/sd...) I erroneously added the whole disk (/dev/sdb) instead of the partition (/dev/sdb1) as part of /dev/md1. I removed the whole disk and correctly added the partition and things were looking just fine at /proc/mdstat so I thought I was over.

However upon rebooting "error: superfluous RAID member (2 found)." was appearing briefly on my screen and the raid array was not reconstructed with my the partitions of the new disk.

I had to zero-out the superblock of /dev/sdb (the disk) with mdadm --zero-superblock /dev/sdb to fix it which also got rig of the "error: superfluous RAID member (2 found)." both from startup and update-grub.

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