More ddf container woes

[Albert Pauw <albert.pauw@gmail.com>]

  Hi Neil,

I found some more trouble with the ddf code, separate from the stuff I 
mentioned before (which is still present in the version I used below).

Here's what I did and found:

Note: Updated mdadm from the git repository up to and including the 
commit "Manage:  be more careful about --add attempts."

Used six disks, sdb - sdg out of which I created a 5-disk container, 
leaving one disk unused for the moment:

mdadm -C /dev/md127 -l container -e ddf -n 5 /dev/sd[b-f]

Created two RAID sets in this container:

mdadm -C /dev/md0 -l 1 -n 2 /dev/md127
mdadm -C /dev/md1 -l 5 -n 3 /dev/md127

Note: At this moment, only one mdmon is running (mdmon md127)

After finishing creating both RAID sets, I fail two disks, one in each 
RAID set:

mdadm -f /dev/md0 /dev/sdb

mdadm -f /dev/md1 /dev/sdd

The first failed disk (sdb) is automatically removed from /dev/md0, but 
oddly enough the disk stays marked as
"active/Online" in the "mdadm -E /dev/md127" output, the second failed 
disk (sdd) gets marked [F] in the RAID 5
array, but NOT removed, only when I do a

mdmon --all

the failed disk in /dev/md1 is removed, this second failed disk IS 
marked "Failed" in the "mdadm -E output".

Note: Checking on the RAID arrays using "mdadm -D" they are both marked 
as "clean, degraded".

I now add a new empty clean disk (/dev/sdg) to the container, after 
which md1 (the RAID 5 set) is immediately starting to rebuild.
The RAID 1 set (md0), however, is set to "resync=DELAYED", very odd, 
because I only added one disk.

Looking at the output of /proc/mdstat i see that disk sdg (the new 
spare) is actually added to both RAID
arrays, and after finishing the rebuild of md1 the other RAID set (md0) 
is also rebuild, using the SAME spare disk (sdg).


Albert