RAID1 with spare preseed error

[Mentler Gyula]

If I try to preseed a RAID with spare I receive an error:
mdadm: You have lister more devices (4) than in the array (3)!

The relevant part of the pressed file contains:
d-i partman-auto-raid/recipe string \
        1 2 1 ext4 / \
                /dev/sda1#/dev/sdb1#/dev/sde1 \
                .

If I do not specify spare there is no error.
d-i partman-auto-raid/recipe string \
        1 2 0 ext4 / \
                /dev/sda1#/dev/sdb1 \
                .

[Stan A. (mozy)]

I came across this while also trying to set up a 2-drive RAID1 with a spare. Weird that this has been opened this long.

I looked through documentation as well as partman source (learned spares is 7th argument) and realized this is not a bug, just wrong syntax on your part. The spare has to be put in its own separate list, so just add a space instead of a # for your last drive/spare device(s) thereby separating it from the devices meant for the array, e.g.:

'''
1 2 1 ext4 / /dev/sda1#/dev/sdb1 /dev/sde1
'''

From the Partman Wiki:
<raidtype> <devcount> <sparecount> <fstype> <mountpoint> <devices> <sparedevices>

Hope this helps whoever googles this next time.