Looked into this more today and found that for some reason my array is
not being detected and assembled correctly after a reboot.
I've got a RAID 5 with 4 disks:
/dev/sdb1
/dev/sdc1
/dev/sdd1
/dev/sde1
Here's what I've accomplished so far:
1) I removed /dev/sde1 using "sudo mdadm /dev/md0 --fail /dev/sde1 --remove
/dev/sde1"
2) I zeroed it's superblock using "sudo mdadm --zero-superblock /dev/sde1"
3) I zeroed the entire disk with "sudo dd if=/dev/zero of=/dev/sde bs=1M"
4) I created a new msdos partition table and added 1 partition using the full
size of the disk with gparted.
5) I reformatted the partition with "sudo mkfs.xfs -f -b size=4096 -d
sunit=128,swidth=384 -L mythtv /dev/sde"
6) Finally, I added the disk back into the raid array using "sudo mdadm
/dev/md0 --add /dev/sde1"
After rebuilding the array on all 4 disks, everything was working. I could
unmount the partition, stop /dev/md0, and then restart it by doing:
sudo umount /media/terabyte
sudo mdadm --stop /dev/md0
sudo mdadm --assemble --scan
This worked fine before a reboot. After rebooting just now, it failed to bring
the array up, giving the familiar error:
"the disk for/mnt/md0 is not ready yet or not present. Continue to wait; or
Press S to skip mount or M for manual recovery."
I logged in and tried to assemble the array, but got this:
-------------------------------------------------------------------------
trinitr...@saturn:~$ sudo mdadm --assemble --scan -v
mdadm: looking for devices for further assembly
mdadm: cannot open device /dev/sdd1: Device or resource busy
mdadm: cannot open device /dev/sdd: Device or resource busy
mdadm: no recogniseable superblock on /dev/sde
mdadm: cannot open device /dev/sdc1: Device or resource busy
mdadm: cannot open device /dev/sdc: Device or resource busy
mdadm: cannot open device /dev/sdb1: Device or resource busy
mdadm: cannot open device /dev/sdb: Device or resource busy
mdadm: cannot open device /dev/sda6: Device or resource busy
mdadm: cannot open device /dev/sda5: Device or resource busy
mdadm: no recogniseable superblock on /dev/sda2
mdadm: cannot open device /dev/sda1: Device or resource busy
mdadm: cannot open device /dev/sda: Device or resource busy
mdadm: No arrays found in config file or automatically
trinitr...@saturn:~$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4]
[raid10]
md0 : inactive sdb1[0](S) sdc1[1](S) sdd1[2](S)
2197715712 blocks
unused devices: <none>
trinitr...@saturn:~$ sudo mdadm --detail /dev/md0
mdadm: md device /dev/md0 does not appear to be active.
-------------------------------------------------------------------------
Now, examining the superblocks on the rest of the disks shows that /dev/sde1 is
missing!!!
Trying to examine /dev/sde1 says that the device does not exist!!
I've repeated this multiple times and cannot figure out what it's problem is.
Here is the superblock information from /dev/sde1 and the first 3 disks:
-------------------------------------------------------------------------
trinitr...@saturn:~$ sudo mdadm --examine /dev/sde1
mdadm: cannot open /dev/sde1: No such file or directory
trinitr...@saturn:~$ sudo mdadm --examine /dev/sdb1
/dev/sdb1:
Magic : a92b4efc
Version : 00.90.00
UUID : 7a0e5ba8:669595fc:852484a6:e390a598 (local to host saturn)
Creation Time : Fri Jan 9 03:40:39 2009
Raid Level : raid5
Used Dev Size : 732571904 (698.64 GiB 750.15 GB)
Array Size : 2197715712 (2095.91 GiB 2250.46 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun May 16 22:13:13 2010
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : b38b3afe - correct
Events : 122066
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 0 8 17 0 active sync /dev/sdb1
0 0 8 17 0 active sync /dev/sdb1
1 1 8 33 1 active sync /dev/sdc1
2 2 8 49 2 active sync /dev/sdd1
3 3 8 65 3 active sync
trinitr...@saturn:~$ sudo mdadm --examine /dev/sdc1
/dev/sdc1:
Magic : a92b4efc
Version : 00.90.00
UUID : 7a0e5ba8:669595fc:852484a6:e390a598 (local to host saturn)
Creation Time : Fri Jan 9 03:40:39 2009
Raid Level : raid5
Used Dev Size : 732571904 (698.64 GiB 750.15 GB)
Array Size : 2197715712 (2095.91 GiB 2250.46 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun May 16 22:13:13 2010
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : b38b3b10 - correct
Events : 122066
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 1 8 33 1 active sync /dev/sdc1
0 0 8 17 0 active sync /dev/sdb1
1 1 8 33 1 active sync /dev/sdc1
2 2 8 49 2 active sync /dev/sdd1
3 3 8 65 3 active sync
trinitr...@saturn:~$ sudo mdadm --examine /dev/sdd1
/dev/sdd1:
Magic : a92b4efc
Version : 00.90.00
UUID : 7a0e5ba8:669595fc:852484a6:e390a598 (local to host saturn)
Creation Time : Fri Jan 9 03:40:39 2009
Raid Level : raid5
Used Dev Size : 732571904 (698.64 GiB 750.15 GB)
Array Size : 2197715712 (2095.91 GiB 2250.46 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun May 16 22:13:13 2010
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : b38b3b22 - correct
Events : 122066
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 2 8 49 2 active sync /dev/sdd1
0 0 8 17 0 active sync /dev/sdb1
1 1 8 33 1 active sync /dev/sdc1
2 2 8 49 2 active sync /dev/sdd1
3 3 8 65 3 active sync
-------------------------------------------------------------------------
Attached is a kernel messages log which shows the array up and running before
the reboot, then after the reboot no array is started. I also examined the
partition tables on the disks, and it seems to be missing for /dev/sde !
-------------------------------------------------------------------------
trinitr...@saturn:/media$ sudo fdisk -l /dev/sde
Disk /dev/sde: 750.2 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/sde doesn't contain a valid partition table
-------------------------------------------------------------------------
Arg!!! This is the 4th time I've had to repartition this disk after a
reboot. Up until the reboot, everything is fine, but something messes
up the partition table of /dev/sde after a reboot.
--
Mdadm array fails to assemble on boot.
https://bugs.launchpad.net/bugs/573477
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