I have a question similar to older thread but I'm not stuck with 100 % CPU usage.I added one more disk (sdd1) to my 5x3TB raid-5 array and upgraded it to raid-6 which all went well until the power supply backplane failed and the server crashed mid-write. mdadm --assemble required a temporary file, which I did specify at the upgrade and with --assemble --temporary-file=, it set the array as active and reshape. Problem is, it's reshaping at 0K/sec and won't finish.The temporary file is zero byte by the way.What are my options? I can access my files at the moment so if I can find 7 TB of storage, I can spend a few days to copy everything, fail and rebuild the array from scratch, but is there a simpler option?Can I fail sdd1 (the new drive I was trying to add) and restart a new five-disk raid-5 to six disk raid-6 array rebuild? Or will that upset the assumed raid-6 array but mostly raid-5 in reality since it didn't finish the raid-5 -> raid-6 reshape?cat /proc/mdstatPersonalities : [raid6] [raid5] [raid4]md127 : active raid6 sdd[0] sdb1[6] sdf[5] sde[3] sda[2] sdc[1]      11721060352 blocks super 1.2 level 6, 512k chunk, algorithm 18 [6/5] [UUUUU_]      [=>...................]  reshape =  8.4% (247529472/2930265088) finish=3353419520.0min speed=0K/secunused devices: <none>
Recover from raid-5 to raid-6 reshape and crash, mdadm reports 0K/sec rebuild
mdadm;md
Try: echo frozen > /sys/block/md127/md/sync_actionecho reshape > /sys/block/md127/md/sync_actionYou'll probably have a degraded RAID-6 (with /dev/sdd missing) at this point, so:run watch cat /proc/mdstat and keep an eye on it until there's no resync or reshape activity.run mdadm --add /dev/md127 /dev/sddrun watch cat /proc/mdstat again.That should get the reshape running at a decent speed.BTW, running cat /proc/mdstat via watch every 2 seconds shouldn't be a significant CPU load, but you probably don't need 2 second updates for something that's going to run for hours.  updating every 10 or 30 seconds should be adequate, e.g. use watch -n 30 cat /proc/mdstat in step 3 above.