On Mon, 14 Oct 2013 21:59:45 -0400 John Yates [off-list ref] wrote:

Midway through a RAID5 grow operation from 5 to 6 USB connected
drives, system logs show that the kernel lost communication with some
of the drive ports which has left my array in a state that I have not
been able to reassemble. After reseating the cable connections and
rebooting, all of the drives appear to be functioning normally, so
hopefully the data is still intact. I need advice on recovery steps
for the array.

It appears that each drive failed in quick succession with /dev/sdc1
being the last standing and having the others marked as missing in its
superblock. The superblocks of the other drives show all drives as
available. (--examine output below)

quoted

mdadm --assemble /dev/md127 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 /dev/sdg1

mdadm: too-old timestamp on backup-metadata on device-5
mdadm: If you think it is should be safe, try 'export MDADM_GROW_ALLOW_OLD=1'
mdadm: /dev/md127 assembled from 1 drives - not enough to start the array.

Did you try following the suggestion and run

 export MDADM_GROW_ALLOW_OLD=1

and the try the --asssemble again?

NeilBrown