I'm using Intrepid and mdadm 2.6.7.

I had a clean stable raid5 array, 5x1tb, before I started. I decided to add another 1tb drive to the array because space was getting low.

I connected the new drive and issued the following commands:

Code:
sudo mdadm --add /dev/md0 /dev/sdg
sudo mdadm --grow /dev/md0 --raid-devices=6
cat /proc/mdstat showed it was going to take ~1600 minutes so I went to bed. When I woke up I had mail with the following:

Code:
A Fail event had been detected on md device /dev/md0.
It could be related to component device /dev/sdf
The array was now reshaping and listed /dev/sdf as a faulty spare. I let it finish the reshape which ended with a faulty spare, failed device.

Next,

Code:
sudo mdadm --manage /dev/md0 --remove /dev/sdf
Now I my status shows the following:

cat /proc/mdstat:
Code:
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md0 : active raid5 sde1[0] sdg[5] sdb1[3] sdd1[2] sdc1[1]
      4883799680 blocks level 5, 64k chunk, algorithm 2 [6/5] [UUUU_U]
sudo mdadm --detail /dev/md0:
Code:
/dev/md0:
        Version : 00.90
  Creation Time : Fri Jan  9 00:03:20 2009
     Raid Level : raid5
     Array Size : 4883799680 (4657.55 GiB 5001.01 GB)
  Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
   Raid Devices : 6
  Total Devices : 5
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Wed Dec 23 08:41:34 2009
          State : clean, degraded
 Active Devices : 5
Working Devices : 5
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 48c840d0:ef028c1b:500c5acc:68ce6167 (local to host eleven)
         Events : 0.1299120

    Number   Major   Minor   RaidDevice State
       0       8       65        0      active sync   /dev/sde1
       1       8       33        1      active sync   /dev/sdc1
       2       8       49        2      active sync   /dev/sdd1
       3       8       17        3      active sync   /dev/sdb1
       4       0        0        4      removed
       5       8       96        5      active sync   /dev/sdg
So my question is, did the grow operation finish, and I just need to add a new drive and let it reshape, then extend my filesystem?

Could I grow (shrink) to one less drive and be back to where I started?