This is so damn frustrating :-| I've spent like 20 hours on this nice error, and seems like dozens of people over Internet too, and no clear solution yet.
I have non-system RAID-5 of 5 disks, and it's fine. But during boot up it says that "/dev/md0 is not ready yet or not present" and asks to press 'S'. Very nice for Ubuntu Server - I have to bring monitor and keyboard to go next.
After this system boots and it's all fine. md0 device works, /proc/mdstat is fine. When I do mount -a - it mounts this array without errors and works fine.
As a dumb and shameful workaround I added noauto in /etc/fstab, and did mounting in /etc/rc.local - it works fine then.
Any hints how to make it work properly?
fstab:
UUID=3588dfed-47ae-4c32-9855-2d69df713b86 /var/bigfatdisk ext4 noauto,noatime,data=writeback,barrier=0,nobh,commit=5 0 0
mdadm config: It is autogenerated:
# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#
# by default, scan all partitions (/proc/partitions) for MD superblocks.
# alternatively, specify devices to scan, using wildcards if desired.
DEVICE partitions
# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes
# automatically tag new arrays as belonging to the local system
HOMEHOST <system>
# instruct the monitoring daemon where to send mail alerts
MAILADDR CENSORED
# definitions of existing MD arrays
ARRAY /dev/md/0 metadata=1.2 bitmap=/var/md0_intent UUID=efccbeb6:a0a65cd6:470dcdf3:62781188 name=LBox2:0
# This file was auto-generated on Mon, 10 Jan 2011 04:06:55 +0200
# by mkconf 3.1.2-2
Partitions:
root@LBox2:/home/px# cat /proc/partitions
major minor #blocks name
8 0 976762584 sda
8 1 976562483 sda1
8 2 131072 sda2
8 16 976762584 sdb
8 17 976562483 sdb1
8 18 131072 sdb2
8 32 78150744 sdc
8 33 74919096 sdc1
8 34 1 sdc2
8 37 3229033 sdc5
8 48 976762584 sdd
8 49 976562483 sdd1
8 50 131072 sdd2
8 64 976762584 sde
8 65 976655593 sde1
8 80 976762584 sdf
8 81 976655593 sdf1
9 0 2929683456 md0
mdstat:
root@LBox2:/home/px# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid6 sda1[0] sdd1[4] sde1[5] sdf1[2] sdb1[1]
2929683456 blocks super 1.2 level 6, 1024k chunk, algorithm 2 [5/5] [UUUUU]
bitmap: 0/8 pages [0KB], 65536KB chunk, file: /var/md0_intent
unused devices: <none>
/proc/partitions
and/proc/mdstat
from the booted system? This sounds like a race condition with mdadm at boot-time.