Array over arrays - how to autoassemble correctly?

["Kristleifur Daðason" <kristleifur@gmail.com>]

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Hi all,

I'm running a RAID-60 array with mdadm. There are two RAID6 arrays,
/dev/md/d0 and d1, and then a RAID0 "meta-array" over that,
/dev/md/tank.

What happens on boot is that the d0 and d1 arrays are assembled, but
the tank array isn't - Ubuntu drops me to a root shell because it
couldn't find the tank partition for mounting from fstab. However, I
just have to do a simple 'mdadm --assemble --scan', and the tank array
pops up instantly and everything is fine.

How do I instruct mdadm to wait for d0 and d1 and do kind of a second
assembly pass to construct tank over them?

/proc/mdstat, output of 'mdadm --detail --scan' and
/etc/mdadm/mdadm.conf are included. I hope that's enough background
information.

Thanks!

-- Kristleifur

[-- Attachment #2: proc.mdstat.txt --]
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Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md127 : active raid0 md_d0[0] md_d1[1]
      11720314368 blocks super 1.1 256k chunks

md_d0 : active raid6 sdh1[2] sdg1[0] sdm1[4] sdk1[5] sdj1[3] sdi1[1]
      5860157440 blocks super 1.1 level 6, 256k chunk, algorithm 2 [6/6] [UUUUUU]

md_d1 : active raid6 sdf1[1] sde1[0] sdl1[3] sdd1[6] sdc1[5] sdb1[4]
      5860157440 blocks super 1.1 level 6, 256k chunk, algorithm 2 [6/6] [UUUUUU]

unused devices: <none>


[-- Attachment #3: mdadm.detail.scan.txt --]
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ARRAY /dev/md/d1 metadata=1.01 name=mamma:d1 UUID=da547022:042a6f68:d5fe251e:5e89f263
ARRAY /dev/md/d0 metadata=1.01 name=mamma:d0 UUID=7f98e926:206a8ebe:59fc8d7b:4644a883
ARRAY /dev/md/tank metadata=1.01 name=mamma:tank UUID=6f98a7a8:d7b50181:587c27d1:59d6d137


[-- Attachment #4: mdadm.conf.txt --]
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# mdadm.conf
#

# by default, scan all partitions (/proc/partitions) for MD superblocks.
# alternatively, specify devices to scan, using wildcards if desired.
DEVICE partitions /dev/md/d0 /dev/md/d1

# auto-create devices with Debian standard permissions
# CREATE owner=root group=disk mode=0660 auto=mdp

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

# definitions of existing MD arrays

ARRAY /dev/md/d0 metadata=1.1 name=mamma:d0 UUID=7f98e926:206a8ebe:59fc8d7b:4644a883 level=raid6 num-devices=6 # container=6f98a7a8:d7b50181:587c27d1:59d6d137

ARRAY /dev/md/d1 metadata=1.1 name=mamma:d1 UUID=da547022:042a6f68:d5fe251e:5e89f263 level=raid6 num-devices=6 # container=6f98a7a8:d7b50181:587c27d1:59d6d137

ARRAY /dev/md/tank metadata=1.1 name=mamma:tank UUID=6f98a7a8:d7b50181:587c27d1:59d6d137 level=raid0 num-devices=2 devices=/dev/md/d0,/dev/md/d1