Consider the following simple RAID1 setup. I have the following two physical disks (lsblk output):

sdb      8:16   0   3.7T  0 disk
sdc      8:32   0   3.7T  0 disk

I created the array with the following command:

# mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb /dev/sdc

This gave me /dev/md0, which I created a file system on and started using.

I then did init 0 and started the machine again the next day.

Now I'm faced with the problem of assembling the array again.

I do this:

# mdadm --assemble /dev/md0 /dev/sdb /dev/sdc
mdadm: /dev/md0 has been started with 1 drive (out of 2).


[  493.602864] md: kicking non-fresh sdb from array!
[  493.602869] md: unbind<sdb>

Nothing else is wrong in dmesg. These are brand new disks too, no I/O errors.

I do a bit of googling and find this:


So I issue:

# mdadm /dev/md0 --add /dev/sdb
mdadm: added /dev/sdb


[  570.743137] RAID1 conf printout:
[  570.743142]  --- wd:1 rd:2
[  570.743146]  disk 0, wo:1, o:1, dev:sdb
[  570.743148]  disk 1, wo:0, o:1, dev:sdc
[  570.743265] md: recovery of RAID array md0
[  570.743268] md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
[  570.743269] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for recovery.
[  570.743271] md: using 128k window, over a total of 3906887360k.

And indeed, it is now rebuilding the array, for no apparent reason.

cat /proc/mdstat                                                   
Personalities : [raid1] 
md0 : active raid1 sdb[2] sdc[1]
      3906887360 blocks super 1.2 [2/1] [_U]
      [>....................]  recovery =  0.0% (2137216/3906887360) finish=334.9min speed=194292K/sec

unused devices: <none>

What am I doing wrong?

Did I issue the wrong commands? Should I have stopped the array before doing init 0? Why is it rebuilding an array that is not broken?

  • What is the exact command you are using to switch to init level 0? Are there any shutdown scripts being run? – Jesusaur Nov 25 '18 at 11:48

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