Dear,

I'm having an annoying problem with mdadm in ubuntu. Currently I have two
disks on a machine and do a raid in two, with two partitions. I have
md0 and md1.

See:

md1 : active raid1 sda2[0] sdb2[1]
930613248 blocks [2/2] [UU]

md0 : active raid1 sda1[0] sdb1[1]
4200896 blocks [2/2] [UU]

The problem is that the disk sda malfunctioned and stopped working.
Another disc was put in its place, partitioned and re-added in
raid using the following commands:

mdadm /dev/md0 --add /dev/sda2
mdadm /dev/md1 --add /dev/sda1


Thus, they were synchronized and to my surprise the partition
sda2 was as "spare". See:

MD0
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1

MD1
Number Major Minor RaidDevice State
0 8 18 0 active sync /dev/sdb2
1 0 0 1 removed

2 8 2 - spare /dev/sda2

I tried to remove this partition (spare) and re-add it to the raid but
The same thing happens. Below is the mdadm.conf is configured as
(no disks spares).

DEVICE partitions
CREATE owner=root group=disk mode=0660 auto=yes
HOMEHOST <system>
MAILADDR root
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=ID...
ARRAY /dev/md1 level=raid1 num-devices=2 UUID=ID...

Has anyone experienced this problem or have any idea how to solve?

Ubuntu 10.04
mdadm 2.6.7.1-1ubuntu15

Leandro Ferreira

When you add a drive it is always added as a spare. Eventually mdraid sees that it is missing a drive and that a spare is available and add it to the raid.