raid1 woes

Lloyd Kvam lkvam at venix.com
Sun Aug 27 20:07:51 EDT 2017


I have a raid1 where the resync operation stalls. It is set up to mirror three drives
with a fourth as a spare. This set up has been working nicely for several year, until
yesterday. I will rotate a drive to off-site storage to protect the data relying on
the raid to maintain 3 live disks.

>From /proc/mdstat
md1 : active raid1 sdc2[6](S) sda2[5] sdb2[4] sdd2[3](F)
      32766904 blocks super 1.2 [3/2] [UU_]
      [======>..............]  recovery = 30.2% (9924224/32766904) finish=5241.7min speed=72K/sec

This looks normal, but it will NOT advance past that block. It shows two live disks
in the array and a resync to bring the 3rd drive current. Unfortunately that 3rd
drive will not finish the recovery.

This happened yesterday to the original spare when I went to rotate a drive out for
off-site storage. The original third drive also stalled when added back to the array.
Today I tried to add a new drive, but am hitting the same problem.

My best guess is that one or both of the live drives is failing. What should I do
next? My plan is to use ddrescue to copy the two live disks to new drives and then
try to start the raid array with the new drives. I am hoping that will allow me to
resync a third drive. Does this make sense?

Is there a better approach?

https://raid.wiki.kernel.org/index.php/Linux_Raid
This seems to be (by far) the best site for background, but they do not address a
stalled recovery in any page that I have found.

Thanks for any advice or suggestions.


-- 
Lloyd Kvam
5 Foliage View
Lebanon, NH 03766
802-448-0836





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