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I succesfully builded up a raid5 array on debian testing (Wheezy). As the manpages and further tell, the array would be created as an out of sync array with just a new spare injected to be repaired. That worked fine. But after the rebuild process, I get daily messages on missing spares - but the array should be raid5 over 3 discs without spare. I think, I only need to tell mdadm, that there is and should be no spare - but how to? mdadm -Dgives

Active Devices:  3
Working Devices: 3
Failed Devices:  0
Spare Devices:   0

and /proc/mdstat reads

md1: active raid5 sda3[0] sdc3[3] sdb3[1]
##### blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]

Any ideas? Thanks in advance

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up vote 13 down vote accepted

Open the /etc/mdadm/mdadm.conf file, find the line that begins with ARRAY /dev/md1 and remove the line immediately following which states 'spares=1'. Then restart mdadm service.

If you did a mdadm --examine --scan to retrieve the array definitions while the md1 array was still rebuilding, one partition was seen as spare at that moment.

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Thank you for your solution. I'm wondering, how the line got there. I know, that on building up (resulting in a rebuilding state) the has one spare - but after successfully rebuilding that line should be automatically removed, shouldn't it? Anyhow - after manually commenting out the line it is working the way I want it to. Thanks! – Bastian Ebeling Mar 18 '11 at 6:30
@Bastian Ebeling: Many tutorials include mdadm --examine --scan >> /etc/mdadm/mdadm.conf in their instructions, just after the array creation (which is still rebuilding), so it includes an extra spare. – forcefsck Mar 18 '11 at 11:13

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