Replacing hard disk on xenserver / linux software RAID

mark as failed disk :

    mdadm --manage /dev/md0 --fail /dev/sdb1 

remove the disk :

    mdadm --manage /dev/md0 --remove /dev/sdb1

change the physical drive, copy the partition, create the exact same partitioning as on/dev/sda :

    sfdisk -d /dev/sda | sfdisk /dev/sdb

add the new drive

    mdadm --manage /dev/md0 --add /dev/sdb1

done, check the progress :

    cat /etc/mdstat

references:

• https://www.howtoforge.com/replacing_hard_disks_in_a_raid1_array