Hi all,

I had a problem that caused my Ubuntu Server 14 to go down, and it now
will not boot.  I added a drive to my raid1 (/dev/md0 -> /boot) + raid6
(/dev/md2 -> /) setup.  I was previously running with /dev/md0 (raid1)
assembled from /dev/sd[a-f]1, and /dev/md2 (raid6) assembled
/dev/sd[a-f]3.  Both partitions from the new drive were successfully
added to the two md arrays, and the raid1 (the smaller of the two)
resync'd successfully it seemed (I think that resync is the correct word
to use, meaning that mdadm is spreading out the data amongst the drives
once an array has been grown).  When resyncing the larger raid6,
however, the sync speed was quite slow (kb's/sec), and got slower and
slower (7kb/sec... 5kb/sec... 3kb/sec... 1kb/sec...) until the system
entirely halted and I eventually turned the power off.  It now will not
boot.

Thanks to Roger Heflin's help, I've booted into a livecd environment
(ubuntu server 18) with all the necessary raid personalities available.

When trying to --assemble md127 (raid6), i get the following error:
"Failure to restore critical section for reshape, sorry.  Perhaps you
needed to specify the --backup-file".  Needless to say, I didn't save a
backup file when adding the drive.

I have attached some diagnostic output here.  It seems that my raid6
array is not being recognized as such.  I'm not sure what the next steps
are - do I need to figure out how to get the resync up and running
again?  Any help would be greatly appreciated.

Many thanks,

Allie