Hotswap remove disk
backup partition table
sfdisk -d /dev/sdb > partitions.sdb
Mark faulty and remove the drive to replace from the array
mdadm -f /dev/md0 /dev/sdb
Look up the Host, Channel, ID and Lun of the drive to replace, by looking in
Remove the drive from the bus:
echo "scsi remove-single-device 0 0 2 0" > /proc/scsi/scsi
Verify that the drive has been correctly removed, by looking in
Unplug the drive from your SCA bay, and insert a new drive
(normally done by udev) Add the new drive to the bus
echo "scsi add-single-device 0 0 2 0" > /proc/scsi/scsi
Restore partition table
sfdisk /dev/sdb < partitions.sdb
Add the drive to your array
mdadm -a /dev/md0 /dev/sdb